diff --git a/common/BUILD.bazel b/common/BUILD.bazel
index 4305e378..0c07f237 100644
--- a/common/BUILD.bazel
+++ b/common/BUILD.bazel
@@ -6,14 +6,14 @@ load(":paths_test.bzl", "paths_test_suite")
 
 ts_project(
     name = "binary",
-    srcs = ["binary.ts"],
+    srcs = ["binary.mts"],
     visibility = ["//visibility:public"],
     deps = ["//:node_modules/@types/node"],
 )
 
 ts_project(
     name = "binary_test_lib",
-    srcs = ["binary_test.ts"],
+    srcs = ["binary_test.mts"],
     testonly = True,
     deps = [
         ":binary",
@@ -28,13 +28,13 @@ jasmine_node_test(
 
 ts_project(
     name = "collections",
-    srcs = ["collections.ts"],
+    srcs = ["collections.mts"],
     visibility = ["//visibility:public"],
 )
 
 ts_project(
     name = "collections_test_lib",
-    srcs = ["collections_test.ts"],
+    srcs = ["collections_test.mts"],
     testonly = True,
     deps = [
         ":collections",
@@ -49,13 +49,13 @@ jasmine_node_test(
 
 ts_project(
     name = "formatters",
-    srcs = ["formatters.ts"],
+    srcs = ["formatters.mts"],
     visibility = ["//visibility:public"],
 )
 
 ts_project(
     name = "formatters_test_lib",
-    srcs = ["formatters_test.ts"],
+    srcs = ["formatters_test.mts"],
     testonly = True,
     deps = [
         ":formatters",
@@ -70,14 +70,14 @@ jasmine_node_test(
 
 ts_project(
     name = "file_system",
-    srcs = ["file_system.ts"],
+    srcs = ["file_system.mts"],
     visibility = ["//visibility:public"],
     deps = ["//:node_modules/@types/node"],
 )
 
 ts_project(
     name = "file_system_fake",
-    srcs = ["file_system_fake.ts"],
+    srcs = ["file_system_fake.mts"],
     visibility = ["//visibility:public"],
     testonly = True,
     deps = [
@@ -88,14 +88,14 @@ ts_project(
 
 ts_project(
     name = "http",
-    srcs = ["http.ts"],
+    srcs = ["http.mts"],
     visibility = ["//visibility:public"],
     deps = ["//:node_modules/@types/node"],
 )
 
 ts_project(
     name = "http_test_lib",
-    srcs = ["http_test.ts"],
+    srcs = ["http_test.mts"],
     testonly = True,
     deps = [
         ":http",
@@ -139,7 +139,7 @@ paths_test_suite(name = "paths_test")
 
 ts_project(
     name = "prerender_annotation_walker",
-    srcs = ["prerender_annotation_walker.ts"],
+    srcs = ["prerender_annotation_walker.mts"],
     visibility = ["//visibility:public"],
     deps = [
         "//common/models:prerender_annotation",
@@ -149,7 +149,7 @@ ts_project(
 
 ts_project(
     name = "prerender_annotation_walker_test_lib",
-    srcs = ["prerender_annotation_walker_test.ts"],
+    srcs = ["prerender_annotation_walker_test.mts"],
     testonly = True,
     data = ["//:node_modules/node-html-parser"],
     deps = [
@@ -167,13 +167,13 @@ jasmine_node_test(
 
 ts_project(
     name = "probably",
-    srcs = ["probably.ts"],
+    srcs = ["probably.mts"],
     visibility = ["//visibility:public"],
 )
 
 ts_project(
     name = "probably_test_lib",
-    srcs = ["probably_test.ts"],
+    srcs = ["probably_test.mts"],
     testonly = True,
     deps = [
         ":probably",
diff --git a/common/binary.ts b/common/binary.mts
similarity index 100%
rename from common/binary.ts
rename to common/binary.mts
diff --git a/common/binary_test.ts b/common/binary_test.mts
similarity index 97%
rename from common/binary_test.ts
rename to common/binary_test.mts
index 9fb68633..c882254b 100644
--- a/common/binary_test.ts
+++ b/common/binary_test.mts
@@ -1,4 +1,4 @@
-import { main as mainReal } from './binary';
+import { main as mainReal } from './binary.mjs';
 
 // Wrap `main`'s type to return its `Promise` to easily `await` it.
 function main(...args: Parameters<typeof mainReal>): Promise<void> {
diff --git a/common/collections.ts b/common/collections.mts
similarity index 100%
rename from common/collections.ts
rename to common/collections.mts
diff --git a/common/collections_test.ts b/common/collections_test.mts
similarity index 95%
rename from common/collections_test.ts
rename to common/collections_test.mts
index ce28c35b..5b70a388 100644
--- a/common/collections_test.ts
+++ b/common/collections_test.mts
@@ -1,4 +1,4 @@
-import { unique } from './collections';
+import { unique } from './collections.mjs';
 
 describe('collections', () => {
     describe('unique()', () => {
diff --git a/common/file_system.ts b/common/file_system.mts
similarity index 100%
rename from common/file_system.ts
rename to common/file_system.mts
diff --git a/common/file_system_fake.ts b/common/file_system_fake.mts
similarity index 97%
rename from common/file_system_fake.ts
rename to common/file_system_fake.mts
index c6684d47..9f9848f1 100644
--- a/common/file_system_fake.ts
+++ b/common/file_system_fake.mts
@@ -1,5 +1,5 @@
 import * as path from 'path';
-import { FileSystem } from './file_system';
+import { FileSystem } from './file_system.mjs';
 
 /**
  * A fake implementation of the `FileSystem` interface which stores everything
diff --git a/common/formatters.ts b/common/formatters.mts
similarity index 100%
rename from common/formatters.ts
rename to common/formatters.mts
diff --git a/common/formatters_test.ts b/common/formatters_test.mts
similarity index 95%
rename from common/formatters_test.ts
rename to common/formatters_test.mts
index 47f2f40c..14d3c74c 100644
--- a/common/formatters_test.ts
+++ b/common/formatters_test.mts
@@ -1,4 +1,4 @@
-import { mdSpacing } from './formatters';
+import { mdSpacing } from './formatters.mjs';
 
 describe('formatters', () => {
     describe('spaceMarkdown()', () => {
diff --git a/common/http.ts b/common/http.mts
similarity index 100%
rename from common/http.ts
rename to common/http.mts
diff --git a/common/http_test.ts b/common/http_test.mts
similarity index 98%
rename from common/http_test.ts
rename to common/http_test.mts
index 61a0b54a..d96c45b6 100644
--- a/common/http_test.ts
+++ b/common/http_test.mts
@@ -1,6 +1,6 @@
 import nodeHttp from 'http';
 import { URL } from 'url';
-import * as http from './http';
+import * as http from './http.mjs';
 
 describe('http', () => {
     describe('get', () => {
diff --git a/common/models/BUILD.bazel b/common/models/BUILD.bazel
index ddca76a4..9f9588d7 100644
--- a/common/models/BUILD.bazel
+++ b/common/models/BUILD.bazel
@@ -3,13 +3,13 @@ load("//tools/typescript:defs.bzl", "ts_project")
 
 ts_project(
     name = "prerender_annotation",
-    srcs = ["prerender_annotation.ts"],
+    srcs = ["prerender_annotation.mts"],
     visibility = ["//visibility:public"],
 )
 
 ts_project(
     name = "prerender_annotation_test_lib",
-    srcs = ["prerender_annotation_test.ts"],
+    srcs = ["prerender_annotation_test.mts"],
     testonly = True,
     deps = [
         ":prerender_annotation",
@@ -24,7 +24,7 @@ jasmine_node_test(
 
 ts_project(
     name = "prerender_annotation_mock",
-    srcs = ["prerender_annotation_mock.ts"],
+    srcs = ["prerender_annotation_mock.mts"],
     testonly = True,
     visibility = ["//visibility:public"],
     deps = [":prerender_annotation"],
@@ -32,13 +32,13 @@ ts_project(
 
 ts_project(
     name = "prerender_metadata",
-    srcs = ["prerender_metadata.ts"],
+    srcs = ["prerender_metadata.mts"],
     visibility = ["//visibility:public"],
 )
 
 ts_project(
     name = "prerender_metadata_test_lib",
-    srcs = ["prerender_metadata_test.ts"],
+    srcs = ["prerender_metadata_test.mts"],
     testonly = True,
     deps = [
         ":prerender_metadata",
@@ -53,7 +53,7 @@ jasmine_node_test(
 
 ts_project(
     name = "prerender_metadata_mock",
-    srcs = ["prerender_metadata_mock.ts"],
+    srcs = ["prerender_metadata_mock.mts"],
     testonly = True,
     visibility = ["//visibility:public"],
     deps = [":prerender_metadata"],
@@ -61,14 +61,14 @@ ts_project(
 
 ts_project(
     name = "prerender_resource",
-    srcs = ["prerender_resource.ts"],
+    srcs = ["prerender_resource.mts"],
     visibility = ["//visibility:public"],
     deps = [":url_path"],
 )
 
 ts_project(
     name = "prerender_resource_test_lib",
-    srcs = ["prerender_resource_test.ts"],
+    srcs = ["prerender_resource_test.mts"],
     testonly = True,
     deps = [
         ":prerender_resource",
@@ -83,12 +83,12 @@ jasmine_node_test(
 
 ts_project(
     name = "url_path",
-    srcs = ["url_path.ts"],
+    srcs = ["url_path.mts"],
 )
 
 ts_project(
     name = "url_path_test_lib",
-    srcs = ["url_path_test.ts"],
+    srcs = ["url_path_test.mts"],
     testonly = True,
     deps = [
         ":url_path",
diff --git a/common/models/prerender_annotation.ts b/common/models/prerender_annotation.mts
similarity index 100%
rename from common/models/prerender_annotation.ts
rename to common/models/prerender_annotation.mts
diff --git a/common/models/prerender_annotation_mock.ts b/common/models/prerender_annotation_mock.mts
similarity index 97%
rename from common/models/prerender_annotation_mock.ts
rename to common/models/prerender_annotation_mock.mts
index 7ef4ed7c..e0b56d75 100644
--- a/common/models/prerender_annotation_mock.ts
+++ b/common/models/prerender_annotation_mock.mts
@@ -3,7 +3,7 @@
  * @see /README.md#Mocking
  */
 
-import { PrerenderAnnotation, ScriptAnnotation, StyleAnnotation } from './prerender_annotation';
+import { PrerenderAnnotation, ScriptAnnotation, StyleAnnotation } from './prerender_annotation.mjs';
 
 /**
  * Mocks a {@link PrerenderAnnotation} object. Since this type is a
diff --git a/common/models/prerender_annotation_test.ts b/common/models/prerender_annotation_test.mts
similarity index 99%
rename from common/models/prerender_annotation_test.ts
rename to common/models/prerender_annotation_test.mts
index 24c0ce0f..36573f10 100644
--- a/common/models/prerender_annotation_test.ts
+++ b/common/models/prerender_annotation_test.mts
@@ -1,4 +1,4 @@
-import { PrerenderAnnotation, createAnnotation, parseAnnotation, ScriptAnnotation, annotationsEqual, StyleAnnotation } from './prerender_annotation';
+import { PrerenderAnnotation, createAnnotation, parseAnnotation, ScriptAnnotation, annotationsEqual, StyleAnnotation } from './prerender_annotation.mjs';
 
 describe('prerender_annotation', () => {
     describe('PrerenderAnnotation', () => {
diff --git a/common/models/prerender_metadata.ts b/common/models/prerender_metadata.mts
similarity index 100%
rename from common/models/prerender_metadata.ts
rename to common/models/prerender_metadata.mts
diff --git a/common/models/prerender_metadata_mock.ts b/common/models/prerender_metadata_mock.mts
similarity index 98%
rename from common/models/prerender_metadata_mock.ts
rename to common/models/prerender_metadata_mock.mts
index b83c2014..5a4eff24 100644
--- a/common/models/prerender_metadata_mock.ts
+++ b/common/models/prerender_metadata_mock.mts
@@ -3,7 +3,7 @@
  * @see /README.md#Mocking
  */
 
-import { PrerenderMetadata, ScriptMetadata } from './prerender_metadata';
+import { PrerenderMetadata, ScriptMetadata } from './prerender_metadata.mjs';
 
 /** Mocks the {@link PrerenderMetadata} object with the given overrides. */
 export function mockPrerenderMetadata(
diff --git a/common/models/prerender_metadata_test.ts b/common/models/prerender_metadata_test.mts
similarity index 98%
rename from common/models/prerender_metadata_test.ts
rename to common/models/prerender_metadata_test.mts
index c1222f50..c4da255a 100644
--- a/common/models/prerender_metadata_test.ts
+++ b/common/models/prerender_metadata_test.mts
@@ -1,4 +1,4 @@
-import { PrerenderMetadata, ScriptMetadata } from './prerender_metadata';
+import { PrerenderMetadata, ScriptMetadata } from './prerender_metadata.mjs';
 
 describe('prerender_metadata', () => {
     describe('PrerenderMetadata', () => {
diff --git a/common/models/prerender_resource.ts b/common/models/prerender_resource.mts
similarity index 98%
rename from common/models/prerender_resource.ts
rename to common/models/prerender_resource.mts
index 7c7bb99b..b57012ff 100644
--- a/common/models/prerender_resource.ts
+++ b/common/models/prerender_resource.mts
@@ -1,4 +1,4 @@
-import { UrlPath } from './url_path';
+import { UrlPath } from './url_path.mjs';
 
 /** Represents a resource to be rendered / generated at a particular path. */
 export class PrerenderResource {
diff --git a/common/models/prerender_resource_test.ts b/common/models/prerender_resource_test.mts
similarity index 96%
rename from common/models/prerender_resource_test.ts
rename to common/models/prerender_resource_test.mts
index 28a091eb..35e048f8 100644
--- a/common/models/prerender_resource_test.ts
+++ b/common/models/prerender_resource_test.mts
@@ -1,4 +1,4 @@
-import { PrerenderResource } from './prerender_resource';
+import { PrerenderResource } from './prerender_resource.mjs';
 
 describe('PrerenderResource', () => {
     describe('of()', () => {
diff --git a/common/models/url_path.ts b/common/models/url_path.mts
similarity index 100%
rename from common/models/url_path.ts
rename to common/models/url_path.mts
diff --git a/common/models/url_path_test.ts b/common/models/url_path_test.mts
similarity index 91%
rename from common/models/url_path_test.ts
rename to common/models/url_path_test.mts
index c8e6fae3..b9ed2680 100644
--- a/common/models/url_path_test.ts
+++ b/common/models/url_path_test.mts
@@ -1,4 +1,4 @@
-import { UrlPath } from './url_path';
+import { UrlPath } from './url_path.mjs';
 
 describe('UrlPath', () => {
     describe('of()', () => {
diff --git a/common/prerender_annotation_walker.ts b/common/prerender_annotation_walker.mts
similarity index 99%
rename from common/prerender_annotation_walker.ts
rename to common/prerender_annotation_walker.mts
index d1a2014e..f28dbba4 100644
--- a/common/prerender_annotation_walker.ts
+++ b/common/prerender_annotation_walker.mts
@@ -1,5 +1,5 @@
 import { CommentNode, HTMLElement, Node } from 'node-html-parser';
-import { parseAnnotation, PrerenderAnnotation } from './models/prerender_annotation';
+import { parseAnnotation, PrerenderAnnotation } from './models/prerender_annotation.mjs';
 
 /**
  * A reference to a `node-html-parser` `Node` which contains a
@@ -138,4 +138,4 @@ function* walk(node: Node, parent?: HTMLElement):
             yield* walk(child, node);
         }
     }
-}
\ No newline at end of file
+}
diff --git a/common/prerender_annotation_walker_test.ts b/common/prerender_annotation_walker_test.mts
similarity index 98%
rename from common/prerender_annotation_walker_test.ts
rename to common/prerender_annotation_walker_test.mts
index 885e5833..b57238b6 100644
--- a/common/prerender_annotation_walker_test.ts
+++ b/common/prerender_annotation_walker_test.mts
@@ -1,6 +1,6 @@
 import { HTMLElement, parse } from 'node-html-parser';
-import { createAnnotation } from './models/prerender_annotation';
-import { walkAllAnnotations } from './prerender_annotation_walker';
+import { createAnnotation } from './models/prerender_annotation.mjs';
+import { walkAllAnnotations } from './prerender_annotation_walker.mjs';
 
 describe('prerender_annotation_walker', () => {
     describe('walkAllAnnotations()', () => {
diff --git a/common/probably.ts b/common/probably.mts
similarity index 100%
rename from common/probably.ts
rename to common/probably.mts
diff --git a/common/probably_test.ts b/common/probably_test.mts
similarity index 96%
rename from common/probably_test.ts
rename to common/probably_test.mts
index 2255fb42..a12c90ed 100644
--- a/common/probably_test.ts
+++ b/common/probably_test.mts
@@ -1,4 +1,4 @@
-import { definitely, Definitely, Probably } from './probably';
+import { definitely, Definitely, Probably } from './probably.mjs';
 
 interface User {
     name: string;
diff --git a/common/testing/BUILD.bazel b/common/testing/BUILD.bazel
index 0246a84f..89e0a66a 100644
--- a/common/testing/BUILD.bazel
+++ b/common/testing/BUILD.bazel
@@ -4,7 +4,7 @@ load("//tools/typescript:defs.bzl", "ts_project")
 
 ts_project(
     name = "binary",
-    srcs = ["binary.ts"],
+    srcs = ["binary.mts"],
     testonly = True,
     visibility = ["//visibility:public"],
     deps = ["//:node_modules/@types/node"],
@@ -12,7 +12,7 @@ ts_project(
 
 ts_project(
     name = "binary_test_lib",
-    srcs = ["binary_test.ts"],
+    srcs = ["binary_test.mts"],
     testonly = True,
     deps = [
         ":binary",
@@ -29,7 +29,7 @@ jasmine_node_test(
 
 ts_project(
     name = "devserver",
-    srcs = ["devserver.ts"],
+    srcs = ["devserver.mts"],
     testonly = True,
     visibility = ["//visibility:public"],
     data = [
@@ -49,7 +49,7 @@ ts_project(
 
 ts_project(
     name = "devserver_test_lib",
-    srcs = ["devserver_test.ts"],
+    srcs = ["devserver_test.mts"],
     testonly = True,
     data = ["//:node_modules/http-status-codes"],
     deps = [
@@ -84,7 +84,7 @@ jasmine_node_test(
 
 ts_project(
     name = "effects",
-    srcs = ["effects.ts"],
+    srcs = ["effects.mts"],
     testonly = True,
     deps = [
         "//:node_modules/@types/jasmine",
@@ -93,7 +93,7 @@ ts_project(
 
 ts_project(
     name = "effects_test_lib",
-    srcs = ["effects_test.ts"],
+    srcs = ["effects_test.mts"],
     testonly = True,
     deps = [
         ":effects",
@@ -108,7 +108,7 @@ jasmine_node_test(
 
 ts_project(
     name = "effect_fake",
-    srcs = ["effect_fake.ts"],
+    srcs = ["effect_fake.mts"],
     testonly = True,
     visibility = ["//visibility:public"],
     deps = [":effects"],
@@ -116,7 +116,7 @@ ts_project(
 
 ts_project(
     name = "effect_fake_test_lib",
-    srcs = ["effect_fake_test.ts"],
+    srcs = ["effect_fake_test.mts"],
     testonly = True,
     deps = [
         ":effects",
@@ -132,7 +132,7 @@ jasmine_node_test(
 
 ts_project(
     name = "effect_tester",
-    srcs = ["effect_tester.ts"],
+    srcs = ["effect_tester.mts"],
     testonly = True,
     visibility = ["//visibility:public"],
     deps = [
@@ -143,7 +143,7 @@ ts_project(
 
 ts_project(
     name = "effect_tester_test_lib",
-    srcs = ["effect_tester_test.ts"],
+    srcs = ["effect_tester_test.mts"],
     testonly = True,
     deps = [
         ":effects",
@@ -160,7 +160,7 @@ jasmine_node_test(
 
 ts_project(
     name = "mocks",
-    srcs = ["mocks.ts"],
+    srcs = ["mocks.mts"],
     testonly = True,
     visibility = ["//visibility:public"],
     deps = ["//:node_modules/@types/jasmine"],
@@ -168,7 +168,7 @@ ts_project(
 
 ts_project(
     name = "mocks_test_lib",
-    srcs = ["mocks_test.ts"],
+    srcs = ["mocks_test.mts"],
     testonly = True,
     deps = [
         ":mocks",
@@ -183,7 +183,7 @@ jasmine_node_test(
 
 ts_project(
     name = "temp_dir",
-    srcs = ["temp_dir.ts"],
+    srcs = ["temp_dir.mts"],
     testonly = True,
     visibility = ["//visibility:public"],
     deps = [
@@ -194,7 +194,7 @@ ts_project(
 
 ts_project(
     name = "temp_dir_test_lib",
-    srcs = ["temp_dir_test.ts"],
+    srcs = ["temp_dir_test.mts"],
     testonly = True,
     deps = [
         ":temp_dir",
@@ -211,13 +211,13 @@ jasmine_node_test(
 
 ts_project(
     name = "test_server",
-    srcs = ["test_server.ts"],
+    srcs = ["test_server.mts"],
     testonly = True,
 )
 
 ts_project(
     name = "test_server_test_lib",
-    srcs = ["test_server_test.ts"],
+    srcs = ["test_server_test.mts"],
     testonly = True,
     deps = [
         ":test_server",
@@ -232,7 +232,7 @@ jasmine_node_test(
 
 ts_project(
     name = "webdriver",
-    srcs = ["webdriver.ts"],
+    srcs = ["webdriver.mts"],
     testonly = True,
     visibility = ["//visibility:public"],
     data = ["//:node_modules/webdriverio"],
@@ -246,7 +246,7 @@ ts_project(
 
 ts_project(
     name = "webdriver_test_lib",
-    srcs = ["webdriver_test.ts"],
+    srcs = ["webdriver_test.mts"],
     testonly = True,
     deps = [
         ":devserver",
diff --git a/common/testing/binary.ts b/common/testing/binary.mts
similarity index 100%
rename from common/testing/binary.ts
rename to common/testing/binary.mts
diff --git a/common/testing/binary_test.ts b/common/testing/binary_test.mts
similarity index 93%
rename from common/testing/binary_test.ts
rename to common/testing/binary_test.mts
index 8ce7e7ce..9dd12ee1 100644
--- a/common/testing/binary_test.ts
+++ b/common/testing/binary_test.mts
@@ -1,6 +1,6 @@
 import { promises as fs } from 'fs';
-import { execBinary } from './binary';
-import { useTempDir } from './temp_dir';
+import { execBinary } from './binary.mjs';
+import { useTempDir } from './temp_dir.mjs';
 
 describe('binary', () => {
     const tmpDir = useTempDir();
diff --git a/common/testing/devserver.ts b/common/testing/devserver.mts
similarity index 98%
rename from common/testing/devserver.ts
rename to common/testing/devserver.mts
index 03c22d56..b8db61f0 100644
--- a/common/testing/devserver.ts
+++ b/common/testing/devserver.mts
@@ -4,9 +4,9 @@ import killTree from 'tree-kill';
 import net from 'net';
 import { URL } from 'url';
 import { promisify } from 'util';
-import * as http from '../http';
-import { Effect, useForAll } from './effects';
-import { TestServer } from './test_server';
+import * as http from '../http.mjs';
+import { Effect, useForAll } from './effects.mjs';
+import { TestServer } from './test_server.mjs';
 
 type Signal = Parameters<ChildProcess['kill']>[0];
 const execFile = promisify(execFileCb);
diff --git a/common/testing/devserver_test.ts b/common/testing/devserver_test.mts
similarity index 94%
rename from common/testing/devserver_test.ts
rename to common/testing/devserver_test.mts
index 115283c4..cf3888b3 100644
--- a/common/testing/devserver_test.ts
+++ b/common/testing/devserver_test.mts
@@ -1,8 +1,8 @@
 import { URL } from 'url';
 import { StatusCodes } from 'http-status-codes';
-import * as http from '../http';
-import { Server, useDevserver } from './devserver';
-import { EffectTester } from './effect_tester';
+import * as http from '../http.mjs';
+import { Server, useDevserver } from './devserver.mjs';
+import { EffectTester } from './effect_tester.mjs';
 
 const devserver = 'common/testing/devserver_test_server.sh';
 
diff --git a/common/testing/effect_fake.ts b/common/testing/effect_fake.mts
similarity index 89%
rename from common/testing/effect_fake.ts
rename to common/testing/effect_fake.mts
index 7c6cfa28..ce552c71 100644
--- a/common/testing/effect_fake.ts
+++ b/common/testing/effect_fake.mts
@@ -1,4 +1,4 @@
-import { Effect } from './effects';
+import { Effect } from './effects.mjs';
 
 /**
  * Creates a fake implementation of an {@link Effect} which holds the provided
diff --git a/common/testing/effect_fake_test.ts b/common/testing/effect_fake_test.mts
similarity index 85%
rename from common/testing/effect_fake_test.ts
rename to common/testing/effect_fake_test.mts
index 43979f2c..e76f6420 100644
--- a/common/testing/effect_fake_test.ts
+++ b/common/testing/effect_fake_test.mts
@@ -1,5 +1,5 @@
-import { Effect } from './effects';
-import { effectFake } from './effect_fake';
+import { Effect } from './effects.mjs';
+import { effectFake } from './effect_fake.mjs';
 
 describe('effect_fake', () => {
     describe('effectFake()', () => {
diff --git a/common/testing/effect_tester.ts b/common/testing/effect_tester.mts
similarity index 99%
rename from common/testing/effect_tester.ts
rename to common/testing/effect_tester.mts
index 880b6478..e1791bc1 100644
--- a/common/testing/effect_tester.ts
+++ b/common/testing/effect_tester.mts
@@ -1,4 +1,4 @@
-import { Effect } from './effects';
+import { Effect } from './effects.mjs';
 
 /**
  * Utility class for testing effects.
diff --git a/common/testing/effect_tester_test.ts b/common/testing/effect_tester_test.mts
similarity index 96%
rename from common/testing/effect_tester_test.ts
rename to common/testing/effect_tester_test.mts
index a77ca476..9eba53fb 100644
--- a/common/testing/effect_tester_test.ts
+++ b/common/testing/effect_tester_test.mts
@@ -1,6 +1,6 @@
-import { useForEach } from './effects';
-import { effectFake } from './effect_fake';
-import { EffectTester } from './effect_tester';
+import { useForEach } from './effects.mjs';
+import { effectFake } from './effect_fake.mjs';
+import { EffectTester } from './effect_tester.mjs';
 
 describe('EffectTester', () => {
     it('tests effects', async () => {
diff --git a/common/testing/effects.ts b/common/testing/effects.mts
similarity index 100%
rename from common/testing/effects.ts
rename to common/testing/effects.mts
diff --git a/common/testing/effects_test.ts b/common/testing/effects_test.mts
similarity index 98%
rename from common/testing/effects_test.ts
rename to common/testing/effects_test.mts
index 0d1cad65..aa5789db 100644
--- a/common/testing/effects_test.ts
+++ b/common/testing/effects_test.mts
@@ -1,4 +1,4 @@
-import { useForAll, useForEach } from './effects';
+import { useForAll, useForEach } from './effects.mjs';
 
 describe('effects', () => {
     describe('useForEach()', () => {
diff --git a/common/testing/mocks.ts b/common/testing/mocks.mts
similarity index 100%
rename from common/testing/mocks.ts
rename to common/testing/mocks.mts
diff --git a/common/testing/mocks_test.ts b/common/testing/mocks_test.mts
similarity index 96%
rename from common/testing/mocks_test.ts
rename to common/testing/mocks_test.mts
index 3a766a63..7cbe1fcc 100644
--- a/common/testing/mocks_test.ts
+++ b/common/testing/mocks_test.mts
@@ -1,4 +1,4 @@
-import { unmockedFunc } from './mocks';
+import { unmockedFunc } from './mocks.mjs';
 
 describe('mocks', () => {
     describe('unmockedFunc()', () => {
diff --git a/common/testing/temp_dir.ts b/common/testing/temp_dir.mts
similarity index 96%
rename from common/testing/temp_dir.ts
rename to common/testing/temp_dir.mts
index 916cc40c..95a85f92 100644
--- a/common/testing/temp_dir.ts
+++ b/common/testing/temp_dir.mts
@@ -1,6 +1,6 @@
 import { promises as fs } from 'fs';
 import { env } from 'process';
-import { Effect, useForEach } from './effects';
+import { Effect, useForEach } from './effects.mjs';
 
 /**
  * Creates an {@link Effect} of a temporary directory. The directory is deleted
diff --git a/common/testing/temp_dir_test.ts b/common/testing/temp_dir_test.mts
similarity index 92%
rename from common/testing/temp_dir_test.ts
rename to common/testing/temp_dir_test.mts
index 18d56502..dad9d267 100644
--- a/common/testing/temp_dir_test.ts
+++ b/common/testing/temp_dir_test.mts
@@ -1,6 +1,6 @@
 import { env } from 'process';
-import { useTempDir } from './temp_dir';
-import { EffectTester } from './effect_tester';
+import { useTempDir } from './temp_dir.mjs';
+import { EffectTester } from './effect_tester.mjs';
 
 const originalTempDir = env['TEST_TMPDIR'];
 describe('temp_dir', () => {
diff --git a/common/testing/test_server.ts b/common/testing/test_server.mts
similarity index 100%
rename from common/testing/test_server.ts
rename to common/testing/test_server.mts
diff --git a/common/testing/test_server_test.ts b/common/testing/test_server_test.mts
similarity index 93%
rename from common/testing/test_server_test.ts
rename to common/testing/test_server_test.mts
index 9c376448..e30e98c1 100644
--- a/common/testing/test_server_test.ts
+++ b/common/testing/test_server_test.mts
@@ -1,4 +1,4 @@
-import { TestServer } from './test_server';
+import { TestServer } from './test_server.mjs';
 
 describe('test_server', () => {
     describe('TestServer', () => {
diff --git a/common/testing/webdriver.ts b/common/testing/webdriver.mts
similarity index 97%
rename from common/testing/webdriver.ts
rename to common/testing/webdriver.mts
index 5cb355fe..24f49dc7 100644
--- a/common/testing/webdriver.ts
+++ b/common/testing/webdriver.mts
@@ -4,8 +4,8 @@
 
 import { remote, ChainablePromiseElement } from 'webdriverio';
 import { env } from 'process';
-import { Effect, useForAll } from './effects';
-import { TestServer } from './test_server';
+import { Effect, useForAll } from './effects.mjs';
+import { TestServer } from './test_server.mjs';
 
 /**
  * Default timeout value to use for WebDriver tests. They can be quite resource
diff --git a/common/testing/webdriver_test.ts b/common/testing/webdriver_test.mts
similarity index 90%
rename from common/testing/webdriver_test.ts
rename to common/testing/webdriver_test.mts
index 3af76560..3d79f549 100644
--- a/common/testing/webdriver_test.ts
+++ b/common/testing/webdriver_test.mts
@@ -1,6 +1,6 @@
-import { useDevserver } from './devserver';
-import { EffectTester } from './effect_tester';
-import { useWebDriver, webDriverTestTimeout } from './webdriver';
+import { useDevserver } from './devserver.mjs';
+import { EffectTester } from './effect_tester.mjs';
+import { useWebDriver, webDriverTestTimeout } from './webdriver.mjs';
 
 describe('webdriver', () => {
     describe('useWebDriver()', () => {
diff --git a/examples/components/BUILD.bazel b/examples/components/BUILD.bazel
index 7be6b26b..cabf7462 100644
--- a/examples/components/BUILD.bazel
+++ b/examples/components/BUILD.bazel
@@ -9,7 +9,7 @@ load("//tools/jasmine:defs.bzl", "jasmine_web_test_suite")
 
 prerender_pages(
     name = "page",
-    src = "page.ts",
+    src = "page.mts",
     tsconfig = "//:tsconfig",
     source_map = True,
     bundle_js = False, # Optimization: No client-side JavaScript on this page.
@@ -19,7 +19,7 @@ prerender_pages(
 
 prerender_component(
     name = "component",
-    srcs = ["component.ts"],
+    srcs = ["component.mts"],
     tsconfig = "//:tsconfig",
     source_map = True,
     lib_deps = [":ts_dep"],
@@ -28,12 +28,12 @@ prerender_component(
 
 ts_project(
     name = "ts_dep",
-    srcs = ["ts_dep.ts"],
+    srcs = ["ts_dep.mts"],
 )
 
 prerender_component(
     name = "dep",
-    srcs = ["dep.ts"],
+    srcs = ["dep.mts"],
     tsconfig = "//:tsconfig",
     source_map = True,
     deps = [":transitive"],
@@ -41,7 +41,7 @@ prerender_component(
 
 prerender_component(
     name = "transitive",
-    srcs = ["transitive.ts"],
+    srcs = ["transitive.mts"],
     tsconfig = "//:tsconfig",
     source_map = True,
 )
@@ -53,7 +53,7 @@ web_resources_devserver(
 
 ts_project(
     name = "test_lib",
-    srcs = ["test.ts"],
+    srcs = ["test.mts"],
     testonly = True,
     deps = [
         "//common/testing:devserver",
diff --git a/examples/components/component.ts b/examples/components/component.mts
similarity index 83%
rename from examples/components/component.ts
rename to examples/components/component.mts
index 9c406279..6cfd18b3 100644
--- a/examples/components/component.ts
+++ b/examples/components/component.mts
@@ -1,5 +1,5 @@
-import { tsDep } from './ts_dep';
-import { render as renderDep } from './dep';
+import { tsDep } from './ts_dep.mjs';
+import { render as renderDep } from './dep.mjs';
 
 /** Prerenders this component using other components. */
 export function render(): string {
diff --git a/examples/components/dep.ts b/examples/components/dep.mts
similarity index 79%
rename from examples/components/dep.ts
rename to examples/components/dep.mts
index bddf8ead..d13dbe67 100644
--- a/examples/components/dep.ts
+++ b/examples/components/dep.mts
@@ -1,4 +1,4 @@
-import { render as renderTransitive } from './transitive';
+import { render as renderTransitive } from './transitive.mjs';
 
 export function render(): string {
     return `
diff --git a/examples/components/page.ts b/examples/components/page.mts
similarity index 88%
rename from examples/components/page.ts
rename to examples/components/page.mts
index 9cba8fb6..a7bc4608 100644
--- a/examples/components/page.ts
+++ b/examples/components/page.mts
@@ -1,5 +1,5 @@
 import { PrerenderResource } from 'rules_prerender';
-import { render as renderComponent } from './component';
+import { render as renderComponent } from './component.mjs';
 
 /** Renders a page using components. */
 export default function*(): Generator<PrerenderResource, void, void> {
diff --git a/examples/components/test.ts b/examples/components/test.mts
similarity index 92%
rename from examples/components/test.ts
rename to examples/components/test.mts
index 7c505751..2262d70a 100644
--- a/examples/components/test.ts
+++ b/examples/components/test.mts
@@ -1,5 +1,5 @@
-import { useDevserver } from '../../common/testing/devserver';
-import { useWebDriver, webDriverTestTimeout } from '../../common/testing/webdriver';
+import { useDevserver } from '../../common/testing/devserver.mjs';
+import { useWebDriver, webDriverTestTimeout } from '../../common/testing/webdriver.mjs';
 
 describe('components', () => {
     const devserver = useDevserver('examples/components/devserver.sh');
diff --git a/examples/components/transitive.ts b/examples/components/transitive.mts
similarity index 100%
rename from examples/components/transitive.ts
rename to examples/components/transitive.mts
diff --git a/examples/components/ts_dep.ts b/examples/components/ts_dep.mts
similarity index 100%
rename from examples/components/ts_dep.ts
rename to examples/components/ts_dep.mts
diff --git a/examples/data/BUILD.bazel b/examples/data/BUILD.bazel
index 643eefbc..0ef16c25 100644
--- a/examples/data/BUILD.bazel
+++ b/examples/data/BUILD.bazel
@@ -4,7 +4,7 @@ load("//tools/jasmine:defs.bzl", "jasmine_web_test_suite")
 
 prerender_pages(
     name = "pages",
-    src = "pages.ts",
+    src = "pages.mts",
     tsconfig = "//:tsconfig",
     source_map = True,
     data = glob(["content/*.txt"]),
@@ -22,7 +22,7 @@ web_resources_devserver(
 
 ts_project(
     name = "test_lib",
-    srcs = ["test.ts"],
+    srcs = ["test.mts"],
     testonly = True,
     deps = [
         "//common/testing:devserver",
diff --git a/examples/data/pages.ts b/examples/data/pages.mts
similarity index 100%
rename from examples/data/pages.ts
rename to examples/data/pages.mts
diff --git a/examples/data/test.ts b/examples/data/test.mts
similarity index 95%
rename from examples/data/test.ts
rename to examples/data/test.mts
index 4d5c1816..177ed6ce 100644
--- a/examples/data/test.ts
+++ b/examples/data/test.mts
@@ -1,5 +1,5 @@
-import { useDevserver } from '../../common/testing/devserver';
-import { useWebDriver, webDriverTestTimeout } from '../../common/testing/webdriver';
+import { useDevserver } from '../../common/testing/devserver.mjs';
+import { useWebDriver, webDriverTestTimeout } from '../../common/testing/webdriver.mjs';
 
 describe('data', () => {
     const devserver = useDevserver('examples/data/devserver.sh');
diff --git a/examples/declarative_shadow_dom/BUILD.bazel b/examples/declarative_shadow_dom/BUILD.bazel
index 1d36c58c..2c8247b2 100644
--- a/examples/declarative_shadow_dom/BUILD.bazel
+++ b/examples/declarative_shadow_dom/BUILD.bazel
@@ -10,7 +10,7 @@ load("//tools/jasmine:defs.bzl", "jasmine_web_test_suite")
 
 prerender_pages(
     name = "site",
-    src = "site.ts",
+    src = "site.mts",
     tsconfig = "//:tsconfig",
     source_map = True,
     lib_deps = ["//:node_modules/rules_prerender"],
@@ -19,7 +19,7 @@ prerender_pages(
 
 prerender_component(
     name = "component",
-    srcs = ["component.ts"],
+    srcs = ["component.mts"],
     tsconfig = "//:tsconfig",
     source_map = True,
     styles = [":styles"],
@@ -39,7 +39,7 @@ web_resources_devserver(
 
 ts_project(
     name = "test_lib",
-    srcs = ["test.ts"],
+    srcs = ["test.mts"],
     data = [":devserver"],
     testonly = True,
     deps = [
diff --git a/examples/declarative_shadow_dom/component.ts b/examples/declarative_shadow_dom/component.mts
similarity index 100%
rename from examples/declarative_shadow_dom/component.ts
rename to examples/declarative_shadow_dom/component.mts
diff --git a/examples/declarative_shadow_dom/site.ts b/examples/declarative_shadow_dom/site.mts
similarity index 90%
rename from examples/declarative_shadow_dom/site.ts
rename to examples/declarative_shadow_dom/site.mts
index 34e527eb..e3672cce 100644
--- a/examples/declarative_shadow_dom/site.ts
+++ b/examples/declarative_shadow_dom/site.mts
@@ -1,5 +1,5 @@
 import { PrerenderResource } from 'rules_prerender';
-import { renderComponent } from './component';
+import { renderComponent } from './component.mjs';
 
 export default async function*(): AsyncGenerator<PrerenderResource, void, void> {
     yield PrerenderResource.of('/index.html', `
diff --git a/examples/declarative_shadow_dom/test.ts b/examples/declarative_shadow_dom/test.mts
similarity index 91%
rename from examples/declarative_shadow_dom/test.ts
rename to examples/declarative_shadow_dom/test.mts
index 196594ff..4bd7b7b4 100644
--- a/examples/declarative_shadow_dom/test.ts
+++ b/examples/declarative_shadow_dom/test.mts
@@ -1,5 +1,5 @@
-import { useDevserver } from '../../common/testing/devserver';
-import { getColor, useWebDriver, webDriverTestTimeout } from '../../common/testing/webdriver';
+import { useDevserver } from '../../common/testing/devserver.mjs';
+import { getColor, useWebDriver, webDriverTestTimeout } from '../../common/testing/webdriver.mjs';
 
 describe('Declarative Shadow DOM', () => {
     const devserver = useDevserver('examples/declarative_shadow_dom/devserver.sh');
diff --git a/examples/external/BUILD.bazel b/examples/external/BUILD.bazel
index 14729cce..fcf1a8ea 100644
--- a/examples/external/BUILD.bazel
+++ b/examples/external/BUILD.bazel
@@ -43,7 +43,7 @@ ts_config(
 
 prerender_pages(
     name = "site",
-    src = "site.ts",
+    src = "site.mts",
     source_map = True,
     tsconfig = "//:tsconfig",
     lib_deps = ["//:node_modules/rules_prerender"],
diff --git a/examples/external/component/BUILD.bazel b/examples/external/component/BUILD.bazel
index 0ff2bc59..707264ba 100644
--- a/examples/external/component/BUILD.bazel
+++ b/examples/external/component/BUILD.bazel
@@ -8,7 +8,7 @@ load(
 
 prerender_component(
     name = "component",
-    srcs = ["component.ts"],
+    srcs = ["component.mts"],
     scripts = [":script"],
     styles = [":style"],
     resources = [":resources"],
@@ -21,7 +21,7 @@ prerender_component(
 
 ts_project(
     name = "script",
-    srcs = ["script.ts"],
+    srcs = ["script.mts"],
     declaration = True,
     source_map = True,
     tsconfig = "//:tsconfig_client",
diff --git a/examples/external/component/component.ts b/examples/external/component/component.mts
similarity index 100%
rename from examples/external/component/component.ts
rename to examples/external/component/component.mts
diff --git a/examples/external/component/script.ts b/examples/external/component/script.mts
similarity index 100%
rename from examples/external/component/script.ts
rename to examples/external/component/script.mts
diff --git a/examples/external/site.ts b/examples/external/site.mts
similarity index 86%
rename from examples/external/site.ts
rename to examples/external/site.mts
index dbb6e6e6..ee207235 100644
--- a/examples/external/site.ts
+++ b/examples/external/site.mts
@@ -1,5 +1,5 @@
 import { PrerenderResource } from 'rules_prerender';
-import { renderComponent } from './component/component';
+import { renderComponent } from './component/component.mjs';
 
 export default function*(): Generator<PrerenderResource, void, void> {
     yield PrerenderResource.of('/index.html', `
diff --git a/examples/external/tsconfig.json b/examples/external/tsconfig.json
index ec2b0998..a467a361 100644
--- a/examples/external/tsconfig.json
+++ b/examples/external/tsconfig.json
@@ -2,7 +2,8 @@
   "exclude": ["**/dist/"],
   "compilerOptions": {
     "target": "ES2020",
-    "module": "CommonJS",
+    "module": "ES2020",
+    "moduleResolution": "node",
     "declaration": true,
     "sourceMap": true,
     "paths": {
diff --git a/examples/extract/BUILD.bazel b/examples/extract/BUILD.bazel
index 55d30ce1..8df291e6 100644
--- a/examples/extract/BUILD.bazel
+++ b/examples/extract/BUILD.bazel
@@ -3,7 +3,7 @@ load("//:index.bzl", "extract_single_resource", "prerender_pages_unbundled")
 
 prerender_pages_unbundled(
     name = "single_resource",
-    src = "single_resource.ts",
+    src = "single_resource.mts",
     tsconfig = "//:tsconfig",
     source_map = True,
     lib_deps = ["//:node_modules/rules_prerender"],
@@ -23,7 +23,7 @@ diff_test(
 
 prerender_pages_unbundled(
     name = "nested_resource",
-    src = "nested_resource.ts",
+    src = "nested_resource.mts",
     tsconfig = "//:tsconfig",
     source_map = True,
     lib_deps = ["//:node_modules/rules_prerender"],
diff --git a/examples/extract/nested_resource.ts b/examples/extract/nested_resource.mts
similarity index 100%
rename from examples/extract/nested_resource.ts
rename to examples/extract/nested_resource.mts
diff --git a/examples/extract/single_resource.ts b/examples/extract/single_resource.mts
similarity index 100%
rename from examples/extract/single_resource.ts
rename to examples/extract/single_resource.mts
diff --git a/examples/javascript/BUILD.bazel b/examples/javascript/BUILD.bazel
index 39dd371e..5c407ec2 100644
--- a/examples/javascript/BUILD.bazel
+++ b/examples/javascript/BUILD.bazel
@@ -4,7 +4,7 @@ load("//tools/jasmine:defs.bzl", "jasmine_web_test_suite")
 
 prerender_pages(
     name = "page",
-    src = "page.js",
+    src = "page.mjs",
     lib_deps = ["//:node_modules/rules_prerender"],
     deps = ["//examples/javascript/component"],
 )
@@ -16,7 +16,7 @@ web_resources_devserver(
 
 ts_project(
     name = "test_lib",
-    srcs = ["test.ts"],
+    srcs = ["test.mts"],
     testonly = True,
     deps = [
         "//common/testing:devserver",
diff --git a/examples/javascript/component/BUILD.bazel b/examples/javascript/component/BUILD.bazel
index d24b86a7..4298ce2a 100644
--- a/examples/javascript/component/BUILD.bazel
+++ b/examples/javascript/component/BUILD.bazel
@@ -3,7 +3,7 @@ load("//:index.bzl", "prerender_component")
 
 prerender_component(
     name = "component",
-    srcs = ["component.js"],
+    srcs = ["component.mjs"],
     lib_deps = [
         ":prerender_lib",
         "//:node_modules/rules_prerender",
@@ -17,21 +17,21 @@ prerender_component(
 
 js_library(
     name = "prerender_lib",
-    srcs = ["prerender_lib.js"],
+    srcs = ["prerender_lib.mjs"],
 )
 
 js_library(
     name = "component_script",
-    srcs = ["component_script.js"],
+    srcs = ["component_script.mjs"],
     deps = [":component_script_dep"],
 )
 
 js_library(
     name = "component_script_dep",
-    srcs = ["component_script_dep.js"],
+    srcs = ["component_script_dep.mjs"],
 )
 
 js_library(
     name = "component_script_unused",
-    srcs = ["component_script_unused.js"],
+    srcs = ["component_script_unused.mjs"],
 )
diff --git a/examples/javascript/component/component.js b/examples/javascript/component/component.mjs
similarity index 73%
rename from examples/javascript/component/component.js
rename to examples/javascript/component/component.mjs
index 143ef06e..30cd39ba 100644
--- a/examples/javascript/component/component.js
+++ b/examples/javascript/component/component.mjs
@@ -1,8 +1,8 @@
-const { includeScript } = require('rules_prerender');
-const { content } = require('./prerender_lib');
+import { includeScript } from 'rules_prerender';
+import { content } from './prerender_lib.mjs';
 
 /** Renders an example component with a script. */
-function renderComponent() {
+export function renderComponent() {
     return `
 <div id="component">${content}</div>
 <div id="component-replace">
@@ -16,11 +16,9 @@ ${includeScript('examples/javascript/component/component_script')}
  * Renders an example component with a script. This is never called and should
  * not be seen in the output. Used to validate tree-shaking of JS scripts.
  */
-function renderUnused() {
+export function renderUnused() {
     return `
 <div>ERROR: Should never be rendered.</div>
 ${includeScript('examples/javascript/component/component_script_unused')}
     `.trim();
 }
-
-module.exports = { renderComponent, renderUnused };
diff --git a/examples/javascript/component/component_script.js b/examples/javascript/component/component_script.mjs
similarity index 100%
rename from examples/javascript/component/component_script.js
rename to examples/javascript/component/component_script.mjs
diff --git a/examples/javascript/component/component_script_dep.js b/examples/javascript/component/component_script_dep.mjs
similarity index 100%
rename from examples/javascript/component/component_script_dep.js
rename to examples/javascript/component/component_script_dep.mjs
diff --git a/examples/javascript/component/component_script_unused.js b/examples/javascript/component/component_script_unused.mjs
similarity index 100%
rename from examples/javascript/component/component_script_unused.js
rename to examples/javascript/component/component_script_unused.mjs
diff --git a/examples/javascript/component/prerender_lib.js b/examples/javascript/component/prerender_lib.mjs
similarity index 51%
rename from examples/javascript/component/prerender_lib.js
rename to examples/javascript/component/prerender_lib.mjs
index d58023e0..e9057927 100644
--- a/examples/javascript/component/prerender_lib.js
+++ b/examples/javascript/component/prerender_lib.mjs
@@ -1,5 +1,3 @@
 /** @fileoverview JS file to be used as a dependency of a prerender library. */
 
-const content = 'Hello from a JS component!';
-
-module.exports = { content };
+export const content = 'Hello from a JS component!';
diff --git a/examples/javascript/page.js b/examples/javascript/page.mjs
similarity index 65%
rename from examples/javascript/page.js
rename to examples/javascript/page.mjs
index 784e0a63..ef257f57 100644
--- a/examples/javascript/page.js
+++ b/examples/javascript/page.mjs
@@ -1,8 +1,8 @@
-const { PrerenderResource } = require('rules_prerender');
-const { renderComponent } = require('./component/component');
+import { PrerenderResource } from 'rules_prerender';
+import { renderComponent } from './component/component.mjs';
 
 /* Renders the page. */
-module.exports = function*() {
+export default function* () {
     yield PrerenderResource.of('/index.html', `
 <!DOCTYPE html>
 <html>
@@ -16,4 +16,4 @@ module.exports = function*() {
     </body>
 </html>
     `.trim());
-};
+}
diff --git a/examples/javascript/test.ts b/examples/javascript/test.mts
similarity index 87%
rename from examples/javascript/test.ts
rename to examples/javascript/test.mts
index d98171c1..4c0cc25c 100644
--- a/examples/javascript/test.ts
+++ b/examples/javascript/test.mts
@@ -1,5 +1,5 @@
-import { useDevserver } from '../../common/testing/devserver';
-import { useWebDriver, webDriverTestTimeout } from '../../common/testing/webdriver';
+import { useDevserver } from '../../common/testing/devserver.mjs';
+import { useWebDriver, webDriverTestTimeout } from '../../common/testing/webdriver.mjs';
 
 describe('JavaScript', () => {
     const devserver = useDevserver('examples/javascript/devserver.sh');
diff --git a/examples/minimal/BUILD.bazel b/examples/minimal/BUILD.bazel
index ba4a4c8a..68b2db77 100644
--- a/examples/minimal/BUILD.bazel
+++ b/examples/minimal/BUILD.bazel
@@ -4,7 +4,7 @@ load("//tools/jasmine:defs.bzl", "jasmine_web_test_suite")
 
 prerender_pages(
     name = "page",
-    src = "page.ts",
+    src = "page.mts",
     tsconfig = "//:tsconfig",
     source_map = True,
     bundle_js = False, # Optimization: No client-side JavaScript on this page.
@@ -16,13 +16,13 @@ prerender_pages(
 
 ts_project(
     name = "dep",
-    srcs = ["dep.ts"],
+    srcs = ["dep.mts"],
     deps = [":transitive"],
 )
 
 ts_project(
     name = "transitive",
-    srcs = ["transitive.ts"],
+    srcs = ["transitive.mts"],
 )
 
 web_resources_devserver(
@@ -32,7 +32,7 @@ web_resources_devserver(
 
 ts_project(
     name = "test_lib",
-    srcs = ["test.ts"],
+    srcs = ["test.mts"],
     testonly = True,
     deps = [
         "//common/testing:devserver",
diff --git a/examples/minimal/dep.ts b/examples/minimal/dep.mts
similarity index 70%
rename from examples/minimal/dep.ts
rename to examples/minimal/dep.mts
index d066fbfe..b29fd9b6 100644
--- a/examples/minimal/dep.ts
+++ b/examples/minimal/dep.mts
@@ -2,4 +2,4 @@
 export const foo = 'foo';
 
 // Re-export a transitive dependency.
-export { bar } from './transitive';
+export { bar } from './transitive.mjs';
diff --git a/examples/minimal/page.ts b/examples/minimal/page.mts
similarity index 93%
rename from examples/minimal/page.ts
rename to examples/minimal/page.mts
index 783f1683..9eeaea25 100644
--- a/examples/minimal/page.ts
+++ b/examples/minimal/page.mts
@@ -1,4 +1,4 @@
-import { bar, foo } from './dep';
+import { bar, foo } from './dep.mjs';
 import { PrerenderResource } from 'rules_prerender';
 
 /** Renders the page. */
diff --git a/examples/minimal/test.ts b/examples/minimal/test.mts
similarity index 86%
rename from examples/minimal/test.ts
rename to examples/minimal/test.mts
index 49a9d255..7cbb475b 100644
--- a/examples/minimal/test.ts
+++ b/examples/minimal/test.mts
@@ -1,5 +1,5 @@
-import { useDevserver } from '../../common/testing/devserver';
-import { useWebDriver, webDriverTestTimeout } from '../../common/testing/webdriver';
+import { useDevserver } from '../../common/testing/devserver.mjs';
+import { useWebDriver, webDriverTestTimeout } from '../../common/testing/webdriver.mjs';
 
 describe('minimal', () => {
     const devserver = useDevserver('examples/minimal/devserver.sh');
diff --git a/examples/minimal/transitive.ts b/examples/minimal/transitive.mts
similarity index 100%
rename from examples/minimal/transitive.ts
rename to examples/minimal/transitive.mts
diff --git a/examples/multi_page/BUILD.bazel b/examples/multi_page/BUILD.bazel
index 79cde98f..7b31c79f 100644
--- a/examples/multi_page/BUILD.bazel
+++ b/examples/multi_page/BUILD.bazel
@@ -10,7 +10,7 @@ load("//tools/jasmine:defs.bzl", "jasmine_web_test_suite")
 
 prerender_pages(
     name = "pages",
-    src = "pages.ts",
+    src = "pages.mts",
     tsconfig = "//:tsconfig",
     source_map = True,
     lib_deps = ["//:node_modules/rules_prerender"],
@@ -26,7 +26,7 @@ css_library(
 
 ts_project(
     name = "script",
-    srcs = ["script.ts"],
+    srcs = ["script.mts"],
     tsconfig = "//:tsconfig_client",
 )
 
@@ -44,7 +44,7 @@ web_resources_devserver(
 
 ts_project(
     name = "test_lib",
-    srcs = ["test.ts"],
+    srcs = ["test.mts"],
     testonly = True,
     deps = [
         "//common/testing:devserver",
diff --git a/examples/multi_page/pages.ts b/examples/multi_page/pages.mts
similarity index 100%
rename from examples/multi_page/pages.ts
rename to examples/multi_page/pages.mts
diff --git a/examples/multi_page/script.ts b/examples/multi_page/script.mts
similarity index 100%
rename from examples/multi_page/script.ts
rename to examples/multi_page/script.mts
diff --git a/examples/multi_page/test.ts b/examples/multi_page/test.mts
similarity index 96%
rename from examples/multi_page/test.ts
rename to examples/multi_page/test.mts
index 9861df83..bcad379c 100644
--- a/examples/multi_page/test.ts
+++ b/examples/multi_page/test.mts
@@ -1,5 +1,5 @@
-import { useDevserver } from '../../common/testing/devserver';
-import { getColor, useWebDriver, webDriverTestTimeout } from '../../common/testing/webdriver';
+import { useDevserver } from '../../common/testing/devserver.mjs';
+import { getColor, useWebDriver, webDriverTestTimeout } from '../../common/testing/webdriver.mjs';
 
 describe('multi_page', () => {
     const devserver = useDevserver('examples/multi_page/devserver.sh');
diff --git a/examples/prerender_resources/BUILD.bazel b/examples/prerender_resources/BUILD.bazel
index a36f3145..086d3b7c 100644
--- a/examples/prerender_resources/BUILD.bazel
+++ b/examples/prerender_resources/BUILD.bazel
@@ -4,19 +4,19 @@ load("//tools/jasmine:defs.bzl", "jasmine_node_test")
 
 ts_project(
     name = "generator",
-    srcs = ["generator.ts"],
+    srcs = ["generator.mts"],
     deps = ["//:node_modules/rules_prerender"],
 )
 
 prerender_resources(
     name = "prerender",
-    entry_point = "./generator.js",
+    entry_point = "./generator.mjs",
     data = [":generator"],
 )
 
 ts_project(
     name = "generator_test",
-    srcs = ["generator_test.ts"],
+    srcs = ["generator_test.mts"],
     testonly = True,
     data = [":prerender"],
     deps = [
diff --git a/examples/prerender_resources/generator.ts b/examples/prerender_resources/generator.mts
similarity index 100%
rename from examples/prerender_resources/generator.ts
rename to examples/prerender_resources/generator.mts
diff --git a/examples/prerender_resources/generator_test.ts b/examples/prerender_resources/generator_test.mts
similarity index 100%
rename from examples/prerender_resources/generator_test.ts
rename to examples/prerender_resources/generator_test.mts
diff --git a/examples/resources/BUILD.bazel b/examples/resources/BUILD.bazel
index 83f7f030..c40b5966 100644
--- a/examples/resources/BUILD.bazel
+++ b/examples/resources/BUILD.bazel
@@ -9,7 +9,7 @@ load("//tools/jasmine:defs.bzl", "jasmine_web_test_suite")
 
 prerender_pages(
     name = "page",
-    src = "page.ts",
+    src = "page.mts",
     tsconfig = "//:tsconfig",
     source_map = True,
     bundle_js = False, # Optimization: No client-side JavaScript on this page.
@@ -36,7 +36,7 @@ web_resources_devserver(
 
 ts_project(
     name = "test_lib",
-    srcs = ["test.ts"],
+    srcs = ["test.mts"],
     testonly = True,
     deps = [
         "//common/testing:devserver",
diff --git a/examples/resources/component/BUILD.bazel b/examples/resources/component/BUILD.bazel
index 4d1109a3..a263f99f 100644
--- a/examples/resources/component/BUILD.bazel
+++ b/examples/resources/component/BUILD.bazel
@@ -3,7 +3,7 @@ load("//:index.bzl", "prerender_component", "web_resources")
 
 prerender_component(
     name = "component",
-    srcs = ["component.ts"],
+    srcs = ["component.mts"],
     tsconfig = "//:tsconfig",
     source_map = True,
     resources = [":resources"],
diff --git a/examples/resources/component/component.ts b/examples/resources/component/component.mts
similarity index 78%
rename from examples/resources/component/component.ts
rename to examples/resources/component/component.mts
index 1e493470..37c08008 100644
--- a/examples/resources/component/component.ts
+++ b/examples/resources/component/component.mts
@@ -1,4 +1,4 @@
-import { renderTransitive } from '../transitive/transitive';
+import { renderTransitive } from '../transitive/transitive.mjs';
 
 export function renderComponent(): string {
     return `
diff --git a/examples/resources/page.ts b/examples/resources/page.mts
similarity index 88%
rename from examples/resources/page.ts
rename to examples/resources/page.mts
index d11b2c76..47e2e01a 100644
--- a/examples/resources/page.ts
+++ b/examples/resources/page.mts
@@ -1,6 +1,6 @@
 import { PrerenderResource } from 'rules_prerender';
-import { renderComponent } from './component/component';
-import { renderTransitive } from './transitive/transitive';
+import { renderComponent } from './component/component.mjs';
+import { renderTransitive } from './transitive/transitive.mjs';
 
 export default function*(): Generator<PrerenderResource, void, void> {
     yield PrerenderResource.of('/index.html', `
diff --git a/examples/resources/test.ts b/examples/resources/test.mts
similarity index 91%
rename from examples/resources/test.ts
rename to examples/resources/test.mts
index 20491a81..df865848 100644
--- a/examples/resources/test.ts
+++ b/examples/resources/test.mts
@@ -1,5 +1,5 @@
-import { useDevserver } from '../../common/testing/devserver';
-import { useWebDriver, webDriverTestTimeout } from '../../common/testing/webdriver';
+import { useDevserver } from '../../common/testing/devserver.mjs';
+import { useWebDriver, webDriverTestTimeout } from '../../common/testing/webdriver.mjs';
 
 describe('resources', () => {
     const devserver = useDevserver('examples/resources/devserver.sh');
diff --git a/examples/resources/transitive/BUILD.bazel b/examples/resources/transitive/BUILD.bazel
index 54cc73af..c04c6c99 100644
--- a/examples/resources/transitive/BUILD.bazel
+++ b/examples/resources/transitive/BUILD.bazel
@@ -2,7 +2,7 @@ load("//:index.bzl", "prerender_component", "web_resources")
 
 prerender_component(
     name = "transitive",
-    srcs = ["transitive.ts"],
+    srcs = ["transitive.mts"],
     tsconfig = "//:tsconfig",
     source_map = True,
     resources = [":resources"],
diff --git a/examples/resources/transitive/transitive.ts b/examples/resources/transitive/transitive.mts
similarity index 100%
rename from examples/resources/transitive/transitive.ts
rename to examples/resources/transitive/transitive.mts
diff --git a/examples/script_isolation/BUILD.bazel b/examples/script_isolation/BUILD.bazel
index 783641ef..8c98797c 100644
--- a/examples/script_isolation/BUILD.bazel
+++ b/examples/script_isolation/BUILD.bazel
@@ -4,7 +4,7 @@ load("//tools/jasmine:defs.bzl", "jasmine_web_test_suite")
 
 prerender_pages(
     name = "site",
-    src = "site.ts",
+    src = "site.mts",
     scripts = [":foo", ":bar"],
     tsconfig = "//:tsconfig",
     source_map = True,
@@ -13,13 +13,13 @@ prerender_pages(
 
 ts_project(
     name = "foo",
-    srcs = ["foo.ts"],
+    srcs = ["foo.mts"],
     tsconfig = "//:tsconfig_client",
 )
 
 ts_project(
     name = "bar",
-    srcs = ["bar.ts"],
+    srcs = ["bar.mts"],
     tsconfig = "//:tsconfig_client",
 )
 
@@ -30,7 +30,7 @@ web_resources_devserver(
 
 ts_project(
     name = "test_lib",
-    srcs = ["test.ts"],
+    srcs = ["test.mts"],
     testonly = True,
     deps = [
         "//:node_modules/@types/jasmine",
diff --git a/examples/script_isolation/bar.ts b/examples/script_isolation/bar.mts
similarity index 100%
rename from examples/script_isolation/bar.ts
rename to examples/script_isolation/bar.mts
diff --git a/examples/script_isolation/foo.ts b/examples/script_isolation/foo.mts
similarity index 100%
rename from examples/script_isolation/foo.ts
rename to examples/script_isolation/foo.mts
diff --git a/examples/script_isolation/site.ts b/examples/script_isolation/site.mts
similarity index 100%
rename from examples/script_isolation/site.ts
rename to examples/script_isolation/site.mts
diff --git a/examples/script_isolation/test.ts b/examples/script_isolation/test.mts
similarity index 93%
rename from examples/script_isolation/test.ts
rename to examples/script_isolation/test.mts
index 3c31350b..b731c56f 100644
--- a/examples/script_isolation/test.ts
+++ b/examples/script_isolation/test.mts
@@ -1,5 +1,5 @@
-import { useDevserver } from '../../common/testing/devserver';
-import { useWebDriver, webDriverTestTimeout } from '../../common/testing/webdriver';
+import { useDevserver } from '../../common/testing/devserver.mjs';
+import { useWebDriver, webDriverTestTimeout } from '../../common/testing/webdriver.mjs';
 
 describe('Script Isolation', () => {
     const devserver = useDevserver('examples/script_isolation/devserver.sh');
diff --git a/examples/scripts/BUILD.bazel b/examples/scripts/BUILD.bazel
index f5ea8bbb..032b0e61 100644
--- a/examples/scripts/BUILD.bazel
+++ b/examples/scripts/BUILD.bazel
@@ -4,7 +4,7 @@ load("//tools/jasmine:defs.bzl", "jasmine_web_test_suite")
 
 prerender_pages(
     name = "page",
-    src = "page.ts",
+    src = "page.mts",
     tsconfig = "//:tsconfig",
     source_map = True,
     lib_deps = ["//:node_modules/rules_prerender"],
@@ -14,7 +14,7 @@ prerender_pages(
 
 ts_project(
     name = "script",
-    srcs = ["script.ts"],
+    srcs = ["script.mts"],
     tsconfig = "//:tsconfig_client",
 )
 
@@ -25,7 +25,7 @@ web_resources_devserver(
 
 ts_project(
     name = "test_lib",
-    srcs = ["test.ts"],
+    srcs = ["test.mts"],
     testonly = True,
     deps = [
         "//common/testing:devserver",
diff --git a/examples/scripts/component/BUILD.bazel b/examples/scripts/component/BUILD.bazel
index bf1013fb..cbc6d8e5 100644
--- a/examples/scripts/component/BUILD.bazel
+++ b/examples/scripts/component/BUILD.bazel
@@ -3,7 +3,7 @@ load("//:index.bzl", "prerender_component")
 
 prerender_component(
     name = "component",
-    srcs = ["component.ts"],
+    srcs = ["component.mts"],
     tsconfig = "//:tsconfig",
     source_map = True,
     lib_deps = ["//:node_modules/rules_prerender"],
@@ -14,6 +14,6 @@ prerender_component(
 
 ts_project(
     name = "component_script",
-    srcs = ["component_script.ts"],
+    srcs = ["component_script.mts"],
     tsconfig = "//:tsconfig_client",
 )
diff --git a/examples/scripts/component/component.ts b/examples/scripts/component/component.mts
similarity index 87%
rename from examples/scripts/component/component.ts
rename to examples/scripts/component/component.mts
index 54a6e280..4d4fc942 100644
--- a/examples/scripts/component/component.ts
+++ b/examples/scripts/component/component.mts
@@ -1,5 +1,5 @@
 import { includeScript } from 'rules_prerender';
-import { renderTransitive } from '../transitive/transitive';
+import { renderTransitive } from '../transitive/transitive.mjs';
 
 /** Renders HTML which expects a JavaScript library to be included. */
 export function renderComponent(): string {
diff --git a/examples/scripts/component/component_script.ts b/examples/scripts/component/component_script.mts
similarity index 100%
rename from examples/scripts/component/component_script.ts
rename to examples/scripts/component/component_script.mts
diff --git a/examples/scripts/page.ts b/examples/scripts/page.mts
similarity index 91%
rename from examples/scripts/page.ts
rename to examples/scripts/page.mts
index a5e3f117..6d14d3d1 100644
--- a/examples/scripts/page.ts
+++ b/examples/scripts/page.mts
@@ -1,5 +1,5 @@
 import { PrerenderResource, includeScript } from 'rules_prerender';
-import { renderComponent } from './component/component';
+import { renderComponent } from './component/component.mjs';
 
 /** Render some HTML with a `<script />` tag. */
 export default function*(): Generator<PrerenderResource, void, void> {
diff --git a/examples/scripts/script.ts b/examples/scripts/script.mts
similarity index 100%
rename from examples/scripts/script.ts
rename to examples/scripts/script.mts
diff --git a/examples/scripts/test.ts b/examples/scripts/test.mts
similarity index 91%
rename from examples/scripts/test.ts
rename to examples/scripts/test.mts
index e7ce0b8a..43bbf6b2 100644
--- a/examples/scripts/test.ts
+++ b/examples/scripts/test.mts
@@ -1,5 +1,5 @@
-import { useDevserver } from '../../common/testing/devserver';
-import { useWebDriver, webDriverTestTimeout } from '../../common/testing/webdriver';
+import { useDevserver } from '../../common/testing/devserver.mjs';
+import { useWebDriver, webDriverTestTimeout } from '../../common/testing/webdriver.mjs';
 
 describe('Scripts', () => {
     const devserver = useDevserver('examples/scripts/devserver.sh');
diff --git a/examples/scripts/transitive/BUILD.bazel b/examples/scripts/transitive/BUILD.bazel
index 4782c7b7..87ae2dbb 100644
--- a/examples/scripts/transitive/BUILD.bazel
+++ b/examples/scripts/transitive/BUILD.bazel
@@ -3,7 +3,7 @@ load("//:index.bzl", "prerender_component")
 
 prerender_component(
     name = "transitive",
-    srcs = ["transitive.ts"],
+    srcs = ["transitive.mts"],
     tsconfig = "//:tsconfig",
     source_map = True,
     lib_deps = ["//:node_modules/rules_prerender"],
@@ -13,6 +13,6 @@ prerender_component(
 
 ts_project(
     name = "transitive_script",
-    srcs = ["transitive_script.ts"],
+    srcs = ["transitive_script.mts"],
     tsconfig = "//:tsconfig_client",
 )
diff --git a/examples/scripts/transitive/transitive.ts b/examples/scripts/transitive/transitive.mts
similarity index 100%
rename from examples/scripts/transitive/transitive.ts
rename to examples/scripts/transitive/transitive.mts
diff --git a/examples/scripts/transitive/transitive_script.ts b/examples/scripts/transitive/transitive_script.mts
similarity index 100%
rename from examples/scripts/transitive/transitive_script.ts
rename to examples/scripts/transitive/transitive_script.mts
diff --git a/examples/shared_chunks/BUILD.bazel b/examples/shared_chunks/BUILD.bazel
index a3039cf9..b299e00c 100644
--- a/examples/shared_chunks/BUILD.bazel
+++ b/examples/shared_chunks/BUILD.bazel
@@ -4,7 +4,7 @@ load("//tools/typescript:defs.bzl", "ts_project")
 
 prerender_pages(
     name = "site",
-    src = "site.ts",
+    src = "site.mts",
     scripts = [":hello", ":goodbye"],
     tsconfig = "//:tsconfig",
     source_map = True,
@@ -13,21 +13,21 @@ prerender_pages(
 
 ts_project(
     name = "hello",
-    srcs = ["hello.ts"],
+    srcs = ["hello.mts"],
     tsconfig = "//:tsconfig_client",
     deps = [":shared"],
 )
 
 ts_project(
     name = "goodbye",
-    srcs = ["goodbye.ts"],
+    srcs = ["goodbye.mts"],
     tsconfig = "//:tsconfig_client",
     deps = [":shared"],
 )
 
 ts_project(
     name = "shared",
-    srcs = ["shared.ts"],
+    srcs = ["shared.mts"],
     tsconfig = "//:tsconfig_client",
 )
 
@@ -38,7 +38,7 @@ web_resources_devserver(
 
 ts_project(
     name = "test_lib",
-    srcs = ["test.ts"],
+    srcs = ["test.mts"],
     testonly = True,
     data = [":site"],
     deps = [
diff --git a/examples/shared_chunks/goodbye.mts b/examples/shared_chunks/goodbye.mts
new file mode 100644
index 00000000..b7ec1423
--- /dev/null
+++ b/examples/shared_chunks/goodbye.mts
@@ -0,0 +1,3 @@
+import { name } from './shared.mjs';
+
+console.log(`Goodbye, ${name}!`);
diff --git a/examples/shared_chunks/goodbye.ts b/examples/shared_chunks/goodbye.ts
deleted file mode 100644
index 34fbb4d4..00000000
--- a/examples/shared_chunks/goodbye.ts
+++ /dev/null
@@ -1,3 +0,0 @@
-import { name } from './shared';
-
-console.log(`Goodbye, ${name}!`);
diff --git a/examples/shared_chunks/hello.mts b/examples/shared_chunks/hello.mts
new file mode 100644
index 00000000..c12f88f0
--- /dev/null
+++ b/examples/shared_chunks/hello.mts
@@ -0,0 +1,3 @@
+import { name } from './shared.mjs';
+
+console.log(`Hello, ${name}!`);
diff --git a/examples/shared_chunks/hello.ts b/examples/shared_chunks/hello.ts
deleted file mode 100644
index e3b177d6..00000000
--- a/examples/shared_chunks/hello.ts
+++ /dev/null
@@ -1,3 +0,0 @@
-import { name } from './shared';
-
-console.log(`Hello, ${name}!`);
diff --git a/examples/shared_chunks/shared.ts b/examples/shared_chunks/shared.mts
similarity index 100%
rename from examples/shared_chunks/shared.ts
rename to examples/shared_chunks/shared.mts
diff --git a/examples/shared_chunks/site.ts b/examples/shared_chunks/site.mts
similarity index 100%
rename from examples/shared_chunks/site.ts
rename to examples/shared_chunks/site.mts
diff --git a/examples/shared_chunks/test.ts b/examples/shared_chunks/test.mts
similarity index 100%
rename from examples/shared_chunks/test.ts
rename to examples/shared_chunks/test.mts
diff --git a/examples/site/about/BUILD.bazel b/examples/site/about/BUILD.bazel
index 43c4f3cc..d7597cc1 100644
--- a/examples/site/about/BUILD.bazel
+++ b/examples/site/about/BUILD.bazel
@@ -2,7 +2,7 @@ load("//:index.bzl", "css_library", "prerender_pages", "web_resources")
 
 prerender_pages(
     name = "about",
-    src = "about.ts",
+    src = "about.mts",
     tsconfig = "//:tsconfig",
     source_map = True,
     lib_deps = [
diff --git a/examples/site/about/about.ts b/examples/site/about/about.mts
similarity index 96%
rename from examples/site/about/about.ts
rename to examples/site/about/about.mts
index aad2a7af..883486c8 100644
--- a/examples/site/about/about.ts
+++ b/examples/site/about/about.mts
@@ -1,7 +1,7 @@
 import { PrerenderResource, inlineStyle } from 'rules_prerender';
 import { polyfillDeclarativeShadowDom } from '@rules_prerender/declarative_shadow_dom';
-import { baseLayout } from '../components/base/base';
-import { srcLink } from '../common/links';
+import { baseLayout } from '../components/base/base.mjs';
+import { srcLink } from '../common/links.mjs';
 
 /** Renders the about page. */
 export default async function*():
diff --git a/examples/site/blog/BUILD.bazel b/examples/site/blog/BUILD.bazel
index 08dc7179..906553e6 100644
--- a/examples/site/blog/BUILD.bazel
+++ b/examples/site/blog/BUILD.bazel
@@ -4,7 +4,7 @@ load("//tools/jasmine:defs.bzl", "jasmine_node_test")
 
 prerender_pages(
     name = "blog",
-    src = "blog.ts",
+    src = "blog.mts",
     tsconfig = "//:tsconfig",
     source_map = True,
     data = glob(["posts/*.md"]) + [
@@ -26,7 +26,7 @@ prerender_pages(
 
 ts_project(
     name = "blog_test_lib",
-    srcs = ["blog_test.ts"],
+    srcs = ["blog_test.mts"],
     testonly = True,
     data = ["//:node_modules/node-html-parser"],
     deps = [
diff --git a/examples/site/blog/blog.ts b/examples/site/blog/blog.mts
similarity index 96%
rename from examples/site/blog/blog.ts
rename to examples/site/blog/blog.mts
index 91072f01..96552f4c 100644
--- a/examples/site/blog/blog.ts
+++ b/examples/site/blog/blog.mts
@@ -3,8 +3,8 @@ import * as path from 'path';
 import mdLib from 'markdown-it';
 import { PrerenderResource } from 'rules_prerender';
 import { polyfillDeclarativeShadowDom } from '@rules_prerender/declarative_shadow_dom';
-import { srcLink } from '../common/links';
-import { baseLayout } from '../components/base/base';
+import { srcLink } from '../common/links.mjs';
+import { baseLayout } from '../components/base/base.mjs';
 
 interface PostMeta {
     fileName: string;
diff --git a/examples/site/blog/blog_test.ts b/examples/site/blog/blog_test.mts
similarity index 98%
rename from examples/site/blog/blog_test.ts
rename to examples/site/blog/blog_test.mts
index 2e925ff8..cf58650f 100644
--- a/examples/site/blog/blog_test.ts
+++ b/examples/site/blog/blog_test.mts
@@ -1,5 +1,5 @@
 import { parse } from 'node-html-parser';
-import renderBlog from './blog';
+import renderBlog from './blog.mjs';
 
 describe('Blog', () => {
     it('generates a list of posts', async () => {
diff --git a/examples/site/common/BUILD.bazel b/examples/site/common/BUILD.bazel
index 194b05fb..8989a512 100644
--- a/examples/site/common/BUILD.bazel
+++ b/examples/site/common/BUILD.bazel
@@ -3,7 +3,7 @@ load("//:index.bzl", "css_library")
 
 ts_project(
     name = "links",
-    srcs = ["links.ts"],
+    srcs = ["links.mts"],
     visibility = ["//examples/site:__subpackages__"],
 )
 
diff --git a/examples/site/common/links.ts b/examples/site/common/links.mts
similarity index 100%
rename from examples/site/common/links.ts
rename to examples/site/common/links.mts
diff --git a/examples/site/components/base/BUILD.bazel b/examples/site/components/base/BUILD.bazel
index 351f4aec..7714f5f7 100644
--- a/examples/site/components/base/BUILD.bazel
+++ b/examples/site/components/base/BUILD.bazel
@@ -4,7 +4,7 @@ load("//tools/jasmine:defs.bzl", "jasmine_node_test")
 
 prerender_component(
     name = "base",
-    srcs = ["base.ts"],
+    srcs = ["base.mts"],
     tsconfig = "//:tsconfig",
     source_map = True,
     data = ["//:node_modules/rules_prerender"],
@@ -25,7 +25,7 @@ css_library(
 
 ts_project(
     name = "base_test_lib",
-    srcs = ["base_test.ts"],
+    srcs = ["base_test.mts"],
     testonly = True,
     data = ["//:node_modules/node-html-parser"],
     deps = [
diff --git a/examples/site/components/base/base.ts b/examples/site/components/base/base.mts
similarity index 88%
rename from examples/site/components/base/base.ts
rename to examples/site/components/base/base.mts
index fa3f5901..0d1d43ec 100644
--- a/examples/site/components/base/base.ts
+++ b/examples/site/components/base/base.mts
@@ -1,6 +1,6 @@
 import { inlineStyle } from 'rules_prerender';
-import { renderHeader } from '../header/header';
-import { renderFooter } from '../footer/footer';
+import { renderHeader } from '../header/header.mjs';
+import { renderFooter } from '../footer/footer.mjs';
 
 /**
  * Provides a basic structure for an HTML page.
diff --git a/examples/site/components/base/base_test.ts b/examples/site/components/base/base_test.mts
similarity index 98%
rename from examples/site/components/base/base_test.ts
rename to examples/site/components/base/base_test.mts
index c06c9f6d..4a1352d6 100644
--- a/examples/site/components/base/base_test.ts
+++ b/examples/site/components/base/base_test.mts
@@ -1,5 +1,5 @@
 import { HTMLElement, parse, NodeType } from 'node-html-parser';
-import { baseLayout } from './base';
+import { baseLayout } from './base.mjs';
 
 describe('base', () => {
     describe('baseLayout()', () => {
diff --git a/examples/site/components/counter/BUILD.bazel b/examples/site/components/counter/BUILD.bazel
index 3acdd011..a2c75465 100644
--- a/examples/site/components/counter/BUILD.bazel
+++ b/examples/site/components/counter/BUILD.bazel
@@ -9,7 +9,7 @@ load("//tools/jasmine:defs.bzl", "jasmine_node_test", "jasmine_web_test_suite")
 
 prerender_component(
     name = "counter",
-    srcs = ["counter_prerender.ts"],
+    srcs = ["counter_prerender.mts"],
     tsconfig = "//:tsconfig",
     source_map = True,
     data = ["//:node_modules/rules_prerender"],
@@ -20,13 +20,13 @@ prerender_component(
 
 ts_project(
     name = "scripts",
-    srcs = ["counter_script.ts"],
+    srcs = ["counter_script.mts"],
     tsconfig = "//:tsconfig_client",
 )
 
 ts_project(
     name = "counter_prerender_test_lib",
-    srcs = ["counter_prerender_test.ts"],
+    srcs = ["counter_prerender_test.mts"],
     testonly = True,
     data = ["//:node_modules/node-html-parser"],
     deps = [
@@ -43,7 +43,7 @@ jasmine_node_test(
 
 prerender_pages(
     name = "counter_test_cases",
-    src = "counter_test_cases.ts",
+    src = "counter_test_cases.mts",
     tsconfig = "//:tsconfig",
     source_map = True,
     testonly = True,
@@ -59,7 +59,7 @@ web_resources_devserver(
 
 ts_project(
     name = "counter_test_lib",
-    srcs = ["counter_test.ts"],
+    srcs = ["counter_test.mts"],
     testonly = True,
     deps = [
         "//common/testing:devserver",
diff --git a/examples/site/components/counter/counter_prerender.ts b/examples/site/components/counter/counter_prerender.mts
similarity index 100%
rename from examples/site/components/counter/counter_prerender.ts
rename to examples/site/components/counter/counter_prerender.mts
diff --git a/examples/site/components/counter/counter_prerender_test.ts b/examples/site/components/counter/counter_prerender_test.mts
similarity index 93%
rename from examples/site/components/counter/counter_prerender_test.ts
rename to examples/site/components/counter/counter_prerender_test.mts
index 3b5c69c0..37fc3af9 100644
--- a/examples/site/components/counter/counter_prerender_test.ts
+++ b/examples/site/components/counter/counter_prerender_test.mts
@@ -1,5 +1,5 @@
 import { parse } from 'node-html-parser';
-import { renderCounter } from './counter_prerender';
+import { renderCounter } from './counter_prerender.mjs';
 
 describe('counter', () => {
     describe('renderCounter()', () => {
diff --git a/examples/site/components/counter/counter_script.ts b/examples/site/components/counter/counter_script.mts
similarity index 100%
rename from examples/site/components/counter/counter_script.ts
rename to examples/site/components/counter/counter_script.mts
diff --git a/examples/site/components/counter/counter_test.ts b/examples/site/components/counter/counter_test.mts
similarity index 98%
rename from examples/site/components/counter/counter_test.ts
rename to examples/site/components/counter/counter_test.mts
index 00d10ce0..4ee93617 100644
--- a/examples/site/components/counter/counter_test.ts
+++ b/examples/site/components/counter/counter_test.mts
@@ -1,5 +1,5 @@
-import { useDevserver } from '../../../../common/testing/devserver';
-import { useWebDriver, webDriverTestTimeout } from '../../../../common/testing/webdriver';
+import { useDevserver } from '../../../../common/testing/devserver.mjs';
+import { useWebDriver, webDriverTestTimeout } from '../../../../common/testing/webdriver.mjs';
 
 describe('Counter', () => {
     const devserver = useDevserver(
diff --git a/examples/site/components/counter/counter_test_cases.ts b/examples/site/components/counter/counter_test_cases.mts
similarity index 95%
rename from examples/site/components/counter/counter_test_cases.ts
rename to examples/site/components/counter/counter_test_cases.mts
index 37557973..1f5a9fc8 100644
--- a/examples/site/components/counter/counter_test_cases.ts
+++ b/examples/site/components/counter/counter_test_cases.mts
@@ -1,5 +1,5 @@
 import { PrerenderResource } from 'rules_prerender';
-import { renderCounter } from './counter_prerender';
+import { renderCounter } from './counter_prerender.mjs';
 
 /** Generates prerendered test cases of the counter. */
 export default function* (): Generator<PrerenderResource, void, void> {
diff --git a/examples/site/components/footer/BUILD.bazel b/examples/site/components/footer/BUILD.bazel
index 553e7272..5e808770 100644
--- a/examples/site/components/footer/BUILD.bazel
+++ b/examples/site/components/footer/BUILD.bazel
@@ -4,7 +4,7 @@ load("//tools/jasmine:defs.bzl", "jasmine_node_test")
 
 prerender_component(
     name = "footer",
-    srcs = ["footer.ts"],
+    srcs = ["footer.mts"],
     tsconfig = "//:tsconfig",
     source_map = True,
     data = ["//:node_modules/rules_prerender"],
@@ -24,7 +24,7 @@ css_library(
 
 ts_project(
     name = "footer_test_lib",
-    srcs = ["footer_test.ts"],
+    srcs = ["footer_test.mts"],
     testonly = True,
     data = ["//:node_modules/node-html-parser"],
     deps = [
diff --git a/examples/site/components/footer/footer.ts b/examples/site/components/footer/footer.mts
similarity index 91%
rename from examples/site/components/footer/footer.ts
rename to examples/site/components/footer/footer.mts
index 1489b2de..be248716 100644
--- a/examples/site/components/footer/footer.ts
+++ b/examples/site/components/footer/footer.mts
@@ -1,5 +1,5 @@
 import { inlineStyle } from 'rules_prerender';
-import { repo } from '../../common/links';
+import { repo } from '../../common/links.mjs';
 
 /** Renders a footer component for the site. */
 export function renderFooter(): string {
diff --git a/examples/site/components/footer/footer_test.ts b/examples/site/components/footer/footer_test.mts
similarity index 91%
rename from examples/site/components/footer/footer_test.ts
rename to examples/site/components/footer/footer_test.mts
index 9e1842bc..e061ccfe 100644
--- a/examples/site/components/footer/footer_test.ts
+++ b/examples/site/components/footer/footer_test.mts
@@ -1,5 +1,5 @@
 import { parse } from 'node-html-parser';
-import { renderFooter } from './footer';
+import { renderFooter } from './footer.mjs';
 
 describe('footer', () => {
     describe('renderFooter()', () => {
diff --git a/examples/site/components/header/BUILD.bazel b/examples/site/components/header/BUILD.bazel
index c95802bd..e7cf059b 100644
--- a/examples/site/components/header/BUILD.bazel
+++ b/examples/site/components/header/BUILD.bazel
@@ -4,7 +4,7 @@ load("//tools/jasmine:defs.bzl", "jasmine_node_test")
 
 prerender_component(
     name = "header",
-    srcs = ["header.ts"],
+    srcs = ["header.mts"],
     tsconfig = "//:tsconfig",
     source_map = True,
     data = ["//:node_modules/rules_prerender"],
@@ -21,7 +21,7 @@ css_library(
 
 ts_project(
     name = "header_test_lib",
-    srcs = ["header_test.ts"],
+    srcs = ["header_test.mts"],
     testonly = True,
     data = ["//:node_modules/node-html-parser"],
     deps = [
diff --git a/examples/site/components/header/header.ts b/examples/site/components/header/header.mts
similarity index 100%
rename from examples/site/components/header/header.ts
rename to examples/site/components/header/header.mts
diff --git a/examples/site/components/header/header_test.ts b/examples/site/components/header/header_test.mts
similarity index 94%
rename from examples/site/components/header/header_test.ts
rename to examples/site/components/header/header_test.mts
index 1fe9859f..cfcad209 100644
--- a/examples/site/components/header/header_test.ts
+++ b/examples/site/components/header/header_test.mts
@@ -1,5 +1,5 @@
 import { parse } from 'node-html-parser';
-import { renderHeader } from './header';
+import { renderHeader } from './header.mjs';
 
 describe('header', () => {
     describe('renderHeader()', () => {
diff --git a/examples/site/counter/BUILD.bazel b/examples/site/counter/BUILD.bazel
index cbafdd73..57cec183 100644
--- a/examples/site/counter/BUILD.bazel
+++ b/examples/site/counter/BUILD.bazel
@@ -2,7 +2,7 @@ load("//:index.bzl", "prerender_pages")
 
 prerender_pages(
     name = "counter",
-    src = "counter.ts",
+    src = "counter.mts",
     tsconfig = "//:tsconfig",
     source_map = True,
     lib_deps = [
diff --git a/examples/site/counter/counter.ts b/examples/site/counter/counter.mts
similarity index 91%
rename from examples/site/counter/counter.ts
rename to examples/site/counter/counter.mts
index 1fb36d49..80b8b539 100644
--- a/examples/site/counter/counter.ts
+++ b/examples/site/counter/counter.mts
@@ -1,8 +1,8 @@
 import { PrerenderResource } from 'rules_prerender';
 import { polyfillDeclarativeShadowDom } from '@rules_prerender/declarative_shadow_dom';
-import { srcLink } from '../common/links';
-import { baseLayout } from '../components/base/base';
-import { renderCounter } from '../components/counter/counter_prerender';
+import { srcLink } from '../common/links.mjs';
+import { baseLayout } from '../components/base/base.mjs';
+import { renderCounter } from '../components/counter/counter_prerender.mjs';
 
 /** Renders the counter page. */
 export default async function*():
diff --git a/examples/site/home/BUILD.bazel b/examples/site/home/BUILD.bazel
index 6b315fde..946b8295 100644
--- a/examples/site/home/BUILD.bazel
+++ b/examples/site/home/BUILD.bazel
@@ -4,7 +4,7 @@ load("//tools/jasmine:defs.bzl", "jasmine_web_test_suite")
 
 prerender_pages(
     name = "home",
-    src = "home.ts",
+    src = "home.mts",
     tsconfig = "//:tsconfig",
     source_map = True,
     lib_deps = [
@@ -26,7 +26,7 @@ web_resources_devserver(
 
 ts_project(
     name = "home_test_lib",
-    srcs = ["home_test.ts"],
+    srcs = ["home_test.mts"],
     testonly = True,
     deps = [
         "//common/testing:devserver",
diff --git a/examples/site/home/home.ts b/examples/site/home/home.mts
similarity index 96%
rename from examples/site/home/home.ts
rename to examples/site/home/home.mts
index f1399e18..8ce46881 100644
--- a/examples/site/home/home.ts
+++ b/examples/site/home/home.mts
@@ -1,7 +1,7 @@
 import { PrerenderResource } from 'rules_prerender';
 import { polyfillDeclarativeShadowDom } from '@rules_prerender/declarative_shadow_dom';
-import { baseLayout } from '../components/base/base';
-import { repo, srcLink } from '../common/links';
+import { baseLayout } from '../components/base/base.mjs';
+import { repo, srcLink } from '../common/links.mjs';
 
 /** Renders the entire home page. */
 export default async function*():
diff --git a/examples/site/home/home_test.ts b/examples/site/home/home_test.mts
similarity index 80%
rename from examples/site/home/home_test.ts
rename to examples/site/home/home_test.mts
index 1b04bf8a..245f661f 100644
--- a/examples/site/home/home_test.ts
+++ b/examples/site/home/home_test.mts
@@ -1,5 +1,5 @@
-import { useDevserver } from '../../../common/testing/devserver';
-import { useWebDriver, webDriverTestTimeout } from '../../../common/testing/webdriver';
+import { useDevserver } from '../../../common/testing/devserver.mjs';
+import { useWebDriver, webDriverTestTimeout } from '../../../common/testing/webdriver.mjs';
 
 describe('home', () => {
     const devserver = useDevserver('examples/site/home/home_devserver.sh');
diff --git a/examples/styles/BUILD.bazel b/examples/styles/BUILD.bazel
index a530c07e..d7e61915 100644
--- a/examples/styles/BUILD.bazel
+++ b/examples/styles/BUILD.bazel
@@ -4,7 +4,7 @@ load("//tools/jasmine:defs.bzl", "jasmine_web_test_suite")
 
 prerender_pages(
     name = "page",
-    src = "page.ts",
+    src = "page.mts",
     tsconfig = "//:tsconfig",
     source_map = True,
     styles = [":styles"],
@@ -30,7 +30,7 @@ web_resources_devserver(
 
 ts_project(
     name = "test_lib",
-    srcs = ["test.ts"],
+    srcs = ["test.mts"],
     testonly = True,
     deps = [
         "//common/testing:devserver",
diff --git a/examples/styles/page.ts b/examples/styles/page.mts
similarity index 100%
rename from examples/styles/page.ts
rename to examples/styles/page.mts
diff --git a/examples/styles/test.ts b/examples/styles/test.mts
similarity index 92%
rename from examples/styles/test.ts
rename to examples/styles/test.mts
index 9c97c714..89500d63 100644
--- a/examples/styles/test.ts
+++ b/examples/styles/test.mts
@@ -1,5 +1,5 @@
-import { useDevserver } from '../../common/testing/devserver';
-import { getColor, useWebDriver } from '../../common/testing/webdriver';
+import { useDevserver } from '../../common/testing/devserver.mjs';
+import { getColor, useWebDriver } from '../../common/testing/webdriver.mjs';
 
 describe('styles', () => {
     const devserver = useDevserver('examples/styles/devserver.sh');
diff --git a/examples/testonly/BUILD.bazel b/examples/testonly/BUILD.bazel
index 863cf867..fb64f1fe 100644
--- a/examples/testonly/BUILD.bazel
+++ b/examples/testonly/BUILD.bazel
@@ -10,7 +10,7 @@ load(
 
 prerender_pages(
     name = "page",
-    src = "page.ts",
+    src = "page.mts",
     tsconfig = "//:tsconfig",
     source_map = True,
     lib_deps = ["//:node_modules/rules_prerender"],
@@ -29,7 +29,7 @@ css_library(
 
 ts_project(
     name = "scripts",
-    srcs = ["page_script.ts"],
+    srcs = ["page_script.mts"],
     testonly = True,
 )
 
diff --git a/examples/testonly/component/BUILD.bazel b/examples/testonly/component/BUILD.bazel
index 0fc0d019..71dab42a 100644
--- a/examples/testonly/component/BUILD.bazel
+++ b/examples/testonly/component/BUILD.bazel
@@ -3,7 +3,7 @@ load("//:index.bzl", "css_library", "prerender_component", "web_resources")
 
 prerender_component(
     name = "component",
-    srcs = ["component.ts"],
+    srcs = ["component.mts"],
     tsconfig = "//:tsconfig",
     source_map = True,
     lib_deps = ["//:node_modules/rules_prerender"],
@@ -17,7 +17,7 @@ prerender_component(
 
 ts_project(
     name = "scripts",
-    srcs = ["component_script.ts"],
+    srcs = ["component_script.mts"],
     testonly = True,
 )
 
diff --git a/examples/testonly/component/component.ts b/examples/testonly/component/component.mts
similarity index 88%
rename from examples/testonly/component/component.ts
rename to examples/testonly/component/component.mts
index ccc13ae4..0f656e7a 100644
--- a/examples/testonly/component/component.ts
+++ b/examples/testonly/component/component.mts
@@ -1,5 +1,5 @@
 import { includeScript, inlineStyle } from 'rules_prerender';
-import { renderTransitive } from '../transitive/transitive';
+import { renderTransitive } from '../transitive/transitive.mjs';
 
 export function renderComponent(): string {
     return `
diff --git a/examples/testonly/component/component_script.ts b/examples/testonly/component/component_script.mts
similarity index 100%
rename from examples/testonly/component/component_script.ts
rename to examples/testonly/component/component_script.mts
diff --git a/examples/testonly/page.ts b/examples/testonly/page.mts
similarity index 92%
rename from examples/testonly/page.ts
rename to examples/testonly/page.mts
index ca339cbc..d2e5ef24 100644
--- a/examples/testonly/page.ts
+++ b/examples/testonly/page.mts
@@ -1,5 +1,5 @@
 import { PrerenderResource, inlineStyle, includeScript } from 'rules_prerender';
-import { renderComponent } from './component/component';
+import { renderComponent } from './component/component.mjs';
 
 export default function*(): Generator<PrerenderResource, void, void> {
     yield PrerenderResource.of('/index.html', `
diff --git a/examples/testonly/page_script.ts b/examples/testonly/page_script.mts
similarity index 100%
rename from examples/testonly/page_script.ts
rename to examples/testonly/page_script.mts
diff --git a/examples/testonly/transitive/BUILD.bazel b/examples/testonly/transitive/BUILD.bazel
index 06f4ffb2..b9f2fa58 100644
--- a/examples/testonly/transitive/BUILD.bazel
+++ b/examples/testonly/transitive/BUILD.bazel
@@ -3,7 +3,7 @@ load("//:index.bzl", "css_library", "prerender_component", "web_resources")
 
 prerender_component(
     name = "transitive",
-    srcs = ["transitive.ts"],
+    srcs = ["transitive.mts"],
     tsconfig = "//:tsconfig",
     source_map = True,
     lib_deps = ["//:node_modules/rules_prerender"],
@@ -16,7 +16,7 @@ prerender_component(
 
 ts_project(
     name = "scripts",
-    srcs = ["transitive_script.ts"],
+    srcs = ["transitive_script.mts"],
     testonly = True,
 )
 
diff --git a/examples/testonly/transitive/transitive.ts b/examples/testonly/transitive/transitive.mts
similarity index 100%
rename from examples/testonly/transitive/transitive.ts
rename to examples/testonly/transitive/transitive.mts
diff --git a/examples/testonly/transitive/transitive_script.ts b/examples/testonly/transitive/transitive_script.mts
similarity index 100%
rename from examples/testonly/transitive/transitive_script.ts
rename to examples/testonly/transitive/transitive_script.mts
diff --git a/examples/tsconfig/BUILD.bazel b/examples/tsconfig/BUILD.bazel
index e617d618..c2fb2ff3 100644
--- a/examples/tsconfig/BUILD.bazel
+++ b/examples/tsconfig/BUILD.bazel
@@ -3,7 +3,7 @@ load("//:index.bzl", "prerender_pages", "web_resources_devserver")
 
 prerender_pages(
     name = "page",
-    src = "page.ts",
+    src = "page.mts",
     tsconfig = "tsconfig.json",
     source_map = True,
     bundle_js = False, # Optimization: No client-side JavaScript on this page.
diff --git a/examples/tsconfig/page.ts b/examples/tsconfig/page.mts
similarity index 100%
rename from examples/tsconfig/page.ts
rename to examples/tsconfig/page.mts
diff --git a/examples/tsconfig/tsconfig.json b/examples/tsconfig/tsconfig.json
index 51eb8c51..e3d649fa 100644
--- a/examples/tsconfig/tsconfig.json
+++ b/examples/tsconfig/tsconfig.json
@@ -4,7 +4,7 @@
 
     /* Basic Options */
     "target": "ES2019",                       /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019', 'ES2020', or 'ESNEXT'. */
-    "module": "commonjs",                     /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */
+    "module": "ES2020",                       /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */
     "lib": ["ES2020", "DOM"],                 /* Specify library files to be included in the compilation. */
     "declaration": true,
     "sourceMap": true,                        /* Generates corresponding '.map' file. */
@@ -18,6 +18,7 @@
       "rules_prerender": ["../../packages/rules_prerender"], // Map `rules_prerender` module to its implementation.
       "rules_prerender/*": ["*"] // Map workspace-relative imports.
     },
+    "moduleResolution": "node",
     "esModuleInterop": true,                  /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
 
     /* Advanced Options */
diff --git a/examples/tsjs/BUILD.bazel b/examples/tsjs/BUILD.bazel
index d6cb1d5b..6ec45e9e 100644
--- a/examples/tsjs/BUILD.bazel
+++ b/examples/tsjs/BUILD.bazel
@@ -5,7 +5,7 @@ load("//tools/jasmine:defs.bzl", "jasmine_web_test_suite")
 
 prerender_pages(
     name = "page",
-    src = "page.ts",
+    src = "page.mts",
     tsconfig = "//:tsconfig",
     source_map = True,
     scripts = [
@@ -21,7 +21,7 @@ prerender_pages(
 
 ts_project(
     name = "ts_parent_script",
-    srcs = ["ts_parent_script.ts"],
+    srcs = ["ts_parent_script.mts"],
     tsconfig = "//:tsconfig_client",
     deps = [":js_child_script"],
 )
@@ -29,20 +29,20 @@ ts_project(
 js_library(
     name = "js_child_script",
     srcs = [
-        "js_child_script.js",
-        "js_child_script.d.ts",
+        "js_child_script.mjs",
+        "js_child_script.d.mts",
     ],
 )
 
 js_library(
     name = "js_parent_script",
-    srcs = ["js_parent_script.js"],
+    srcs = ["js_parent_script.mjs"],
     deps = [":ts_child_script"],
 )
 
 ts_project(
     name = "ts_child_script",
-    srcs = ["ts_child_script.ts"],
+    srcs = ["ts_child_script.mts"],
     tsconfig = "//:tsconfig_client",
 )
 
@@ -53,7 +53,7 @@ web_resources_devserver(
 
 ts_project(
     name = "test_lib",
-    srcs = ["test.ts"],
+    srcs = ["test.mts"],
     data = [":devserver"],
     testonly = True,
     deps = [
diff --git a/examples/tsjs/js_child/BUILD.bazel b/examples/tsjs/js_child/BUILD.bazel
index 07cb3c04..8efae572 100644
--- a/examples/tsjs/js_child/BUILD.bazel
+++ b/examples/tsjs/js_child/BUILD.bazel
@@ -3,8 +3,8 @@ load("//:index.bzl", "prerender_component")
 prerender_component(
     name = "js_child",
     srcs = [
-        "js_child.js",
-        "js_child.d.ts",
+        "js_child.mjs",
+        "js_child.d.mts",
     ],
     visibility = ["//examples/tsjs:__subpackages__"],
 )
diff --git a/examples/tsjs/js_child/js_child.d.ts b/examples/tsjs/js_child/js_child.d.mts
similarity index 100%
rename from examples/tsjs/js_child/js_child.d.ts
rename to examples/tsjs/js_child/js_child.d.mts
diff --git a/examples/tsjs/js_child/js_child.js b/examples/tsjs/js_child/js_child.mjs
similarity index 57%
rename from examples/tsjs/js_child/js_child.js
rename to examples/tsjs/js_child/js_child.mjs
index 4650d0bc..6108ec26 100644
--- a/examples/tsjs/js_child/js_child.js
+++ b/examples/tsjs/js_child/js_child.mjs
@@ -1,9 +1,7 @@
-function renderJsChild() {
+export function renderJsChild() {
     return `
 <div class="js-child">
     <span>JS child</span>
 </div>
     `.trim();
 }
-
-module.exports = { renderJsChild };
diff --git a/examples/tsjs/js_child_script.d.ts b/examples/tsjs/js_child_script.d.mts
similarity index 100%
rename from examples/tsjs/js_child_script.d.ts
rename to examples/tsjs/js_child_script.d.mts
diff --git a/examples/tsjs/js_child_script.js b/examples/tsjs/js_child_script.mjs
similarity index 100%
rename from examples/tsjs/js_child_script.js
rename to examples/tsjs/js_child_script.mjs
diff --git a/examples/tsjs/js_parent/BUILD.bazel b/examples/tsjs/js_parent/BUILD.bazel
index b0cbb8ef..31c6742a 100644
--- a/examples/tsjs/js_parent/BUILD.bazel
+++ b/examples/tsjs/js_parent/BUILD.bazel
@@ -3,8 +3,8 @@ load("//:index.bzl", "prerender_component")
 prerender_component(
     name = "js_parent",
     srcs = [
-        "js_parent.js",
-        "js_parent.d.ts",
+        "js_parent.mjs",
+        "js_parent.d.mts",
     ],
     visibility = ["//examples/tsjs:__subpackages__"],
     deps = ["//examples/tsjs/ts_child"],
diff --git a/examples/tsjs/js_parent/js_parent.d.ts b/examples/tsjs/js_parent/js_parent.d.mts
similarity index 100%
rename from examples/tsjs/js_parent/js_parent.d.ts
rename to examples/tsjs/js_parent/js_parent.d.mts
diff --git a/examples/tsjs/js_parent/js_parent.js b/examples/tsjs/js_parent/js_parent.js
deleted file mode 100644
index 5d63dace..00000000
--- a/examples/tsjs/js_parent/js_parent.js
+++ /dev/null
@@ -1,12 +0,0 @@
-const { renderTsChild } = require('../ts_child/ts_child');
-
-function renderJsParent() {
-    return `
-<div class="js-parent">
-    <span>JS parent</span>
-    ${renderTsChild()}
-</div>
-    `.trim();
-}
-
-module.exports = { renderJsParent };
diff --git a/examples/tsjs/js_parent/js_parent.mjs b/examples/tsjs/js_parent/js_parent.mjs
new file mode 100644
index 00000000..46166e13
--- /dev/null
+++ b/examples/tsjs/js_parent/js_parent.mjs
@@ -0,0 +1,10 @@
+import { renderTsChild } from '../ts_child/ts_child.mjs';
+
+export function renderJsParent() {
+    return `
+<div class="js-parent">
+    <span>JS parent</span>
+    ${renderTsChild()}
+</div>
+    `.trim();
+}
diff --git a/examples/tsjs/js_parent_script.js b/examples/tsjs/js_parent_script.mjs
similarity index 100%
rename from examples/tsjs/js_parent_script.js
rename to examples/tsjs/js_parent_script.mjs
diff --git a/examples/tsjs/page.ts b/examples/tsjs/page.mts
similarity index 95%
rename from examples/tsjs/page.ts
rename to examples/tsjs/page.mts
index 98780ab6..c7b12da0 100644
--- a/examples/tsjs/page.ts
+++ b/examples/tsjs/page.mts
@@ -1,6 +1,6 @@
 import { PrerenderResource, includeScript } from 'rules_prerender';
-import { renderJsParent } from './js_parent/js_parent';
-import { renderTsParent } from './ts_parent/ts_parent';
+import { renderJsParent } from './js_parent/js_parent.mjs';
+import { renderTsParent } from './ts_parent/ts_parent.mjs';
 
 export default function*(): Generator<PrerenderResource, void, void> {
     // Index page to list the various test cases.
diff --git a/examples/tsjs/test.ts b/examples/tsjs/test.mts
similarity index 95%
rename from examples/tsjs/test.ts
rename to examples/tsjs/test.mts
index 790dd7c9..1945f12f 100644
--- a/examples/tsjs/test.ts
+++ b/examples/tsjs/test.mts
@@ -1,5 +1,5 @@
-import { useDevserver } from '../../common/testing/devserver';
-import { useWebDriver, webDriverTestTimeout } from '../../common/testing/webdriver';
+import { useDevserver } from '../../common/testing/devserver.mjs';
+import { useWebDriver, webDriverTestTimeout } from '../../common/testing/webdriver.mjs';
 
 describe('TS/JS', () => {
     const devserver = useDevserver('examples/tsjs/devserver.sh');
diff --git a/examples/tsjs/ts_child/BUILD.bazel b/examples/tsjs/ts_child/BUILD.bazel
index f30f4747..0747ddaf 100644
--- a/examples/tsjs/ts_child/BUILD.bazel
+++ b/examples/tsjs/ts_child/BUILD.bazel
@@ -2,7 +2,7 @@ load("//:index.bzl", "prerender_component")
 
 prerender_component(
     name = "ts_child",
-    srcs = ["ts_child.ts"],
+    srcs = ["ts_child.mts"],
     tsconfig = "//:tsconfig",
     source_map = True,
     visibility = ["//examples/tsjs:__subpackages__"],
diff --git a/examples/tsjs/ts_child/ts_child.ts b/examples/tsjs/ts_child/ts_child.mts
similarity index 100%
rename from examples/tsjs/ts_child/ts_child.ts
rename to examples/tsjs/ts_child/ts_child.mts
diff --git a/examples/tsjs/ts_child_script.ts b/examples/tsjs/ts_child_script.mts
similarity index 100%
rename from examples/tsjs/ts_child_script.ts
rename to examples/tsjs/ts_child_script.mts
diff --git a/examples/tsjs/ts_parent/BUILD.bazel b/examples/tsjs/ts_parent/BUILD.bazel
index ddaeb49d..91bbc0dd 100644
--- a/examples/tsjs/ts_parent/BUILD.bazel
+++ b/examples/tsjs/ts_parent/BUILD.bazel
@@ -2,7 +2,7 @@ load("//:index.bzl", "prerender_component")
 
 prerender_component(
     name = "ts_parent",
-    srcs = ["ts_parent.ts"],
+    srcs = ["ts_parent.mts"],
     tsconfig = "//:tsconfig",
     source_map = True,
     visibility = ["//examples/tsjs:__subpackages__"],
diff --git a/examples/tsjs/ts_parent/ts_parent.ts b/examples/tsjs/ts_parent/ts_parent.mts
similarity index 72%
rename from examples/tsjs/ts_parent/ts_parent.ts
rename to examples/tsjs/ts_parent/ts_parent.mts
index 3d65c080..61efca76 100644
--- a/examples/tsjs/ts_parent/ts_parent.ts
+++ b/examples/tsjs/ts_parent/ts_parent.mts
@@ -1,4 +1,4 @@
-import { renderJsChild } from '../js_child/js_child';
+import { renderJsChild } from '../js_child/js_child.mjs';
 
 export function renderTsParent(): string {
     return `
diff --git a/examples/tsjs/ts_parent_script.ts b/examples/tsjs/ts_parent_script.mts
similarity index 72%
rename from examples/tsjs/ts_parent_script.ts
rename to examples/tsjs/ts_parent_script.mts
index 4ed031a1..58db83ef 100644
--- a/examples/tsjs/ts_parent_script.ts
+++ b/examples/tsjs/ts_parent_script.mts
@@ -1,4 +1,4 @@
-import { target } from './js_child_script';
+import { target } from './js_child_script.mjs';
 
 const replace = document.getElementById('replace-ts-parent-script');
 if (replace) replace.innerText = `Hello, ${target}!`;
diff --git a/package.json b/package.json
index 729d48ff..d1655977 100644
--- a/package.json
+++ b/package.json
@@ -1,8 +1,9 @@
 {
     "name": "rules_prerender",
     "version": "0.0.0-PLACEHOLDER",
-    "main": "./packages/rules_prerender/index.js",
-    "typings": "./packages/rules_prerender/index.d.ts",
+    "main": "./packages/rules_prerender/index.mjs",
+    "typings": "./packages/rules_prerender/index.d.mts",
+    "type": "module",
     "engines": {
         "node": "^18.12.1",
         "npm": "^8.19.1",
diff --git a/packages/declarative_shadow_dom/BUILD.bazel b/packages/declarative_shadow_dom/BUILD.bazel
index 758d0005..f96c7264 100644
--- a/packages/declarative_shadow_dom/BUILD.bazel
+++ b/packages/declarative_shadow_dom/BUILD.bazel
@@ -37,7 +37,7 @@ npm_publish(
 
 prerender_component(
     name = "declarative_shadow_dom",
-    srcs = ["declarative_shadow_dom.ts"],
+    srcs = ["declarative_shadow_dom.mts"],
     tsconfig = "//:tsconfig",
     source_map = True,
     scripts = [":declarative_shadow_dom_polyfill"],
@@ -50,7 +50,7 @@ prerender_component(
 
 ts_project(
     name = "declarative_shadow_dom_test_lib",
-    srcs = ["declarative_shadow_dom_test.ts"],
+    srcs = ["declarative_shadow_dom_test.mts"],
     testonly = True,
     deps = [
         ":declarative_shadow_dom_prerender_for_test",
@@ -66,6 +66,6 @@ jasmine_node_test(
 
 ts_project(
     name = "declarative_shadow_dom_polyfill",
-    srcs = ["declarative_shadow_dom_polyfill.ts"],
+    srcs = ["declarative_shadow_dom_polyfill.mts"],
     tsconfig = "//:tsconfig_client",
 )
diff --git a/packages/declarative_shadow_dom/declarative_shadow_dom.ts b/packages/declarative_shadow_dom/declarative_shadow_dom.mts
similarity index 100%
rename from packages/declarative_shadow_dom/declarative_shadow_dom.ts
rename to packages/declarative_shadow_dom/declarative_shadow_dom.mts
diff --git a/packages/declarative_shadow_dom/declarative_shadow_dom_polyfill.ts b/packages/declarative_shadow_dom/declarative_shadow_dom_polyfill.mts
similarity index 100%
rename from packages/declarative_shadow_dom/declarative_shadow_dom_polyfill.ts
rename to packages/declarative_shadow_dom/declarative_shadow_dom_polyfill.mts
diff --git a/packages/declarative_shadow_dom/declarative_shadow_dom_test.ts b/packages/declarative_shadow_dom/declarative_shadow_dom_test.mts
similarity index 95%
rename from packages/declarative_shadow_dom/declarative_shadow_dom_test.ts
rename to packages/declarative_shadow_dom/declarative_shadow_dom_test.mts
index f10ecf46..7e3e38c3 100644
--- a/packages/declarative_shadow_dom/declarative_shadow_dom_test.ts
+++ b/packages/declarative_shadow_dom/declarative_shadow_dom_test.mts
@@ -1,5 +1,5 @@
-import { createAnnotation } from '../../common/models/prerender_annotation';
-import { polyfillDeclarativeShadowDom } from './declarative_shadow_dom';
+import { createAnnotation } from '../../common/models/prerender_annotation.mjs';
+import { polyfillDeclarativeShadowDom } from './declarative_shadow_dom.mjs';
 
 describe('declarative_shadow_dom', () => {
     describe('polyfillDeclarativeShadowDom()', () => {
diff --git a/packages/declarative_shadow_dom/package.json b/packages/declarative_shadow_dom/package.json
index 258f941b..a248a655 100644
--- a/packages/declarative_shadow_dom/package.json
+++ b/packages/declarative_shadow_dom/package.json
@@ -1,7 +1,8 @@
 {
     "name": "@rules_prerender/declarative_shadow_dom",
     "version": "0.0.0-PLACEHOLDER",
-    "main": "./declarative_shadow_dom",
+    "type": "module",
+    "main": "./declarative_shadow_dom.mjs",
     "peerDependencies": {
         "rules_prerender": "^0.0.0-PLACEHOLDER"
     }
diff --git a/packages/rules_prerender/BUILD.bazel b/packages/rules_prerender/BUILD.bazel
index 9279b31d..462f74e9 100644
--- a/packages/rules_prerender/BUILD.bazel
+++ b/packages/rules_prerender/BUILD.bazel
@@ -6,6 +6,11 @@ load("//:index.bzl", "prerender_component")
 load("//tools/jasmine:defs.bzl", "jasmine_node_test")
 load("//tools/typescript:defs.bzl", "ts_project")
 
+# Unused `package.json` file exists for IDE intellisense of imports in
+# `//examples/external/...`. This is necessary to have a `main` field which
+# points at `index.mts.`
+exports_files(["package.json"], visibility = ["//visibility:private"])
+
 rollup_bin.rollup_binary(
     name = "rollup",
     visibility = ["//visibility:public"],
@@ -18,7 +23,7 @@ http_server_bin.http_server_binary(
 
 ts_project(
     name = "rollup_config",
-    srcs = ["rollup.config.ts"],
+    srcs = ["rollup.config.mts"],
     visibility = ["//visibility:public"],
     deps = [
         "//:node_modules/@rollup/plugin-node-resolve",
@@ -28,7 +33,7 @@ ts_project(
 
 ts_project(
     name = "rules_prerender_lib",
-    srcs = ["index.ts"],
+    srcs = ["index.mts"],
     visibility = ["//:__pkg__"],
     deps = [
         ":scripts",
@@ -88,7 +93,7 @@ bzl_library(
 
 ts_project(
     name = "prerender_component_publish_files_test_lib",
-    srcs = ["prerender_component_publish_files_test.ts"],
+    srcs = ["prerender_component_publish_files_test.mts"],
     data = ["//packages/rules_prerender/prerender_component_publish_files_testdata:component_publish_files"],
     deps = [
         "//:node_modules/@types/jasmine",
@@ -157,13 +162,13 @@ bzl_library(
 
 ts_project(
     name = "scripts",
-    srcs = ["scripts.ts"],
+    srcs = ["scripts.mts"],
     deps = ["//common/models:prerender_annotation"],
 )
 
 ts_project(
     name = "scripts_test_lib",
-    srcs = ["scripts_test.ts"],
+    srcs = ["scripts_test.mts"],
     testonly = True,
     deps = [
         ":scripts",
@@ -179,7 +184,7 @@ jasmine_node_test(
 
 ts_project(
     name = "styles",
-    srcs = ["styles.ts"],
+    srcs = ["styles.mts"],
     visibility = ["//packages/renderer:__subpackages__"],
     deps = [
         ":inline_style_map",
@@ -189,7 +194,7 @@ ts_project(
 
 ts_project(
     name = "styles_test_lib",
-    srcs = ["styles_test.ts"],
+    srcs = ["styles_test.mts"],
     testonly = True,
     deps = [
         ":inline_style_map",
@@ -206,6 +211,6 @@ jasmine_node_test(
 
 ts_project(
     name = "inline_style_map",
-    srcs = ["inline_style_map.ts"],
+    srcs = ["inline_style_map.mts"],
     visibility = ["//packages/renderer:__subpackages__"],
 )
diff --git a/packages/rules_prerender/index.ts b/packages/rules_prerender/index.mts
similarity index 72%
rename from packages/rules_prerender/index.ts
rename to packages/rules_prerender/index.mts
index b63edabd..1bb1ce64 100644
--- a/packages/rules_prerender/index.ts
+++ b/packages/rules_prerender/index.mts
@@ -1,7 +1,7 @@
 /** @fileoverview Re-exports public symbols. */
 
-export { PrerenderResource } from '../../common/models/prerender_resource';
-export { includeScript } from './scripts';
-export { inlineStyle, InlineStyleNotFoundError as InternalInlineStyleNotFoundError } from './styles';
+export { PrerenderResource } from '../../common/models/prerender_resource.mjs';
+export { includeScript } from './scripts.mjs';
+export { inlineStyle, InlineStyleNotFoundError as InternalInlineStyleNotFoundError } from './styles.mjs';
 
-export { setMap as internalSetInlineStyleMap, resetMapForTesting as internalResetInlineStyleMapForTesting } from './inline_style_map';
+export { setMap as internalSetInlineStyleMap, resetMapForTesting as internalResetInlineStyleMapForTesting } from './inline_style_map.mjs';
diff --git a/packages/rules_prerender/inline_style_map.ts b/packages/rules_prerender/inline_style_map.mts
similarity index 100%
rename from packages/rules_prerender/inline_style_map.ts
rename to packages/rules_prerender/inline_style_map.mts
diff --git a/packages/rules_prerender/package.json b/packages/rules_prerender/package.json
new file mode 100644
index 00000000..068c6966
--- /dev/null
+++ b/packages/rules_prerender/package.json
@@ -0,0 +1,6 @@
+{
+    "name": "rules_prerender",
+    "version": "0.0.0-PLACEHOLDER",
+    "type": "module",
+    "main": "./index.mjs"
+}
diff --git a/packages/rules_prerender/prerender_component_publish_files_test.ts b/packages/rules_prerender/prerender_component_publish_files_test.mts
similarity index 72%
rename from packages/rules_prerender/prerender_component_publish_files_test.ts
rename to packages/rules_prerender/prerender_component_publish_files_test.mts
index 93dab656..21f09f5c 100644
--- a/packages/rules_prerender/prerender_component_publish_files_test.ts
+++ b/packages/rules_prerender/prerender_component_publish_files_test.mts
@@ -6,18 +6,18 @@ describe('prerender_component_publish_files()', () => {
     it('includes exactly the expected files', async () => {
         // Should include **exactly** these files and no more.
         const expectedFiles = new Set([
-            'component.js',
-            'component.js.map',
-            'component.d.ts',
-            'prerender_dep.js',
-            'prerender_dep.js.map',
-            'prerender_dep.d.ts',
-            'script.js',
-            'script.js.map',
-            'script.d.ts',
-            'script_dep.js',
-            'script_dep.js.map',
-            'script_dep.d.ts',
+            'component.mjs',
+            'component.mjs.map',
+            'component.d.mts',
+            'prerender_dep.mjs',
+            'prerender_dep.mjs.map',
+            'prerender_dep.d.mts',
+            'script.mjs',
+            'script.mjs.map',
+            'script.d.mts',
+            'script_dep.mjs',
+            'script_dep.mjs.map',
+            'script_dep.d.mts',
             // Temporary bad assertion. Need to update component publishing to copy
             // styles into the correct position in the NPM package.
             'component_styles_bin_binary_0',
diff --git a/packages/rules_prerender/prerender_component_publish_files_testdata/BUILD.bazel b/packages/rules_prerender/prerender_component_publish_files_testdata/BUILD.bazel
index e891a648..e5ba13a7 100644
--- a/packages/rules_prerender/prerender_component_publish_files_testdata/BUILD.bazel
+++ b/packages/rules_prerender/prerender_component_publish_files_testdata/BUILD.bazel
@@ -10,7 +10,7 @@ load("//tools/typescript:defs.bzl", "ts_project")
 
 prerender_component(
     name = "component",
-    srcs = ["component.ts"],
+    srcs = ["component.mts"],
     tsconfig = "//:tsconfig",
     source_map = True,
     lib_deps = [":prerender_dep"],
@@ -21,12 +21,12 @@ prerender_component(
 
 ts_project(
     name = "prerender_dep",
-    srcs = ["prerender_dep.ts"],
+    srcs = ["prerender_dep.mts"],
 )
 
 ts_project(
     name = "scripts",
-    srcs = ["script.ts"],
+    srcs = ["script.mts"],
     deps = [":script_dep"],
 )
 
@@ -37,7 +37,7 @@ css_library(
 
 ts_project(
     name = "script_dep",
-    srcs = ["script_dep.ts"],
+    srcs = ["script_dep.mts"],
 )
 
 web_resources(
diff --git a/packages/rules_prerender/prerender_component_publish_files_testdata/component.ts b/packages/rules_prerender/prerender_component_publish_files_testdata/component.mts
similarity index 100%
rename from packages/rules_prerender/prerender_component_publish_files_testdata/component.ts
rename to packages/rules_prerender/prerender_component_publish_files_testdata/component.mts
diff --git a/packages/rules_prerender/prerender_component_publish_files_testdata/prerender_dep.ts b/packages/rules_prerender/prerender_component_publish_files_testdata/prerender_dep.mts
similarity index 100%
rename from packages/rules_prerender/prerender_component_publish_files_testdata/prerender_dep.ts
rename to packages/rules_prerender/prerender_component_publish_files_testdata/prerender_dep.mts
diff --git a/packages/rules_prerender/prerender_component_publish_files_testdata/script.ts b/packages/rules_prerender/prerender_component_publish_files_testdata/script.mts
similarity index 56%
rename from packages/rules_prerender/prerender_component_publish_files_testdata/script.ts
rename to packages/rules_prerender/prerender_component_publish_files_testdata/script.mts
index eccf9454..618ec9f3 100644
--- a/packages/rules_prerender/prerender_component_publish_files_testdata/script.ts
+++ b/packages/rules_prerender/prerender_component_publish_files_testdata/script.mts
@@ -1,4 +1,4 @@
-import { bar } from './script_dep';
+import { bar } from './script_dep.mjs';
 
 export function foo(): string {
     return bar();
diff --git a/packages/rules_prerender/prerender_component_publish_files_testdata/script_dep.ts b/packages/rules_prerender/prerender_component_publish_files_testdata/script_dep.mts
similarity index 100%
rename from packages/rules_prerender/prerender_component_publish_files_testdata/script_dep.ts
rename to packages/rules_prerender/prerender_component_publish_files_testdata/script_dep.mts
diff --git a/packages/rules_prerender/prerender_resources.bzl b/packages/rules_prerender/prerender_resources.bzl
index 0733fd07..0dfd2c82 100644
--- a/packages/rules_prerender/prerender_resources.bzl
+++ b/packages/rules_prerender/prerender_resources.bzl
@@ -94,21 +94,21 @@ def prerender_resources_internal(
                 + " format: \"path/to/pkg/file.js\"") % entry_point)
 
     # Generate binary entry point.
-    binary_entry = "%s_binary_entry.js" % name
+    binary_entry = "%s_binary_entry.mjs" % name
     write_file(
         name = "%s_binary_entry" % name,
         out = binary_entry,
         content = ["""
-const rulesPrerender = require('rules_prerender');
-const {{ main }} = require('{binary_helper}');
-const {{ createRenderer }} = require('{renderer}');
-const mod = require('{entry_point}');
+import * as rulesPrerender from 'rules_prerender';
+import {{ main }} from '{binary_helper}';
+import {{ createRenderer }} from '{renderer}';
+import * as mod from '{entry_point}';
 
 const render = createRenderer(rulesPrerender, mod, '{entry_point}');
 main(render);
         """.format(
-            binary_helper = rel_path(file_path_of(Label("//common:binary"))),
-            renderer = rel_path(file_path_of(Label("//tools/binaries/renderer"))),
+            binary_helper = rel_path(file_path_of(Label("//common:binary"))) + ".mjs",
+            renderer = rel_path(file_path_of(Label("//tools/binaries/renderer"))) + ".mjs",
             entry_point = entry_point,
         ).strip()],
         testonly = testonly,
diff --git a/packages/rules_prerender/rollup.config.ts b/packages/rules_prerender/rollup.config.mts
similarity index 100%
rename from packages/rules_prerender/rollup.config.ts
rename to packages/rules_prerender/rollup.config.mts
diff --git a/packages/rules_prerender/scripts.ts b/packages/rules_prerender/scripts.mts
similarity index 96%
rename from packages/rules_prerender/scripts.ts
rename to packages/rules_prerender/scripts.mts
index 0d24b554..722bfa38 100644
--- a/packages/rules_prerender/scripts.ts
+++ b/packages/rules_prerender/scripts.mts
@@ -1,4 +1,4 @@
-import { createAnnotation } from '../../common/models/prerender_annotation';
+import { createAnnotation } from '../../common/models/prerender_annotation.mjs';
 
 /**
  * Returns a prerender annotation as a string to be included in prerendered
diff --git a/packages/rules_prerender/scripts_test.ts b/packages/rules_prerender/scripts_test.mts
similarity index 87%
rename from packages/rules_prerender/scripts_test.ts
rename to packages/rules_prerender/scripts_test.mts
index 2369fe88..55eebdff 100644
--- a/packages/rules_prerender/scripts_test.ts
+++ b/packages/rules_prerender/scripts_test.mts
@@ -1,5 +1,5 @@
-import { createAnnotation } from '../../common/models/prerender_annotation';
-import { includeScript } from './scripts';
+import { createAnnotation } from '../../common/models/prerender_annotation.mjs';
+import { includeScript } from './scripts.mjs';
 
 describe('scripts', () => {
     describe('includeScript()', () => {
diff --git a/packages/rules_prerender/styles.ts b/packages/rules_prerender/styles.mts
similarity index 96%
rename from packages/rules_prerender/styles.ts
rename to packages/rules_prerender/styles.mts
index dfacc6a7..e272b8fa 100644
--- a/packages/rules_prerender/styles.ts
+++ b/packages/rules_prerender/styles.mts
@@ -1,5 +1,5 @@
-import { createAnnotation } from '../../common/models/prerender_annotation';
-import { getMap as getInlineStyleMap } from './inline_style_map';
+import { createAnnotation } from '../../common/models/prerender_annotation.mjs';
+import { getMap as getInlineStyleMap } from './inline_style_map.mjs';
 
 /**
  * Returns a prerender annotation as a string to be included in prerendered
diff --git a/packages/rules_prerender/styles_test.ts b/packages/rules_prerender/styles_test.mts
similarity index 91%
rename from packages/rules_prerender/styles_test.ts
rename to packages/rules_prerender/styles_test.mts
index ad39f937..19f16605 100644
--- a/packages/rules_prerender/styles_test.ts
+++ b/packages/rules_prerender/styles_test.mts
@@ -1,6 +1,6 @@
-import * as inlineStyleMap from './inline_style_map';
-import { createAnnotation } from '../../common/models/prerender_annotation';
-import { inlineStyle, InlineStyleNotFoundError } from './styles';
+import * as inlineStyleMap from './inline_style_map.mjs';
+import { createAnnotation } from '../../common/models/prerender_annotation.mjs';
+import { inlineStyle, InlineStyleNotFoundError } from './styles.mjs';
 
 describe('styles', () => {
     describe('inlineStyle()', () => {
diff --git a/tools/binaries/annotation_extractor/BUILD.bazel b/tools/binaries/annotation_extractor/BUILD.bazel
index 4a8c2de3..40b55f51 100644
--- a/tools/binaries/annotation_extractor/BUILD.bazel
+++ b/tools/binaries/annotation_extractor/BUILD.bazel
@@ -4,14 +4,14 @@ load("//tools/typescript:defs.bzl", "ts_project")
 
 js_binary(
     name = "annotation_extractor",
-    entry_point = "annotation_extractor.js",
+    entry_point = "annotation_extractor.mjs",
     visibility = ["//visibility:public"],
     data = [":annotation_extractor_lib"],
 )
 
 ts_project(
     name = "annotation_extractor_lib",
-    srcs = ["annotation_extractor.ts"],
+    srcs = ["annotation_extractor.mts"],
     data = ["//:node_modules/yargs"],
     deps = [
         ":extractor",
@@ -27,7 +27,7 @@ ts_project(
 
 ts_project(
     name = "annotation_extractor_test_lib",
-    srcs = ["annotation_extractor_test.ts"],
+    srcs = ["annotation_extractor_test.mts"],
     testonly = True,
     deps = [
         "//common/models:prerender_annotation",
@@ -48,7 +48,7 @@ jasmine_node_test(
 
 ts_project(
     name = "extractor",
-    srcs = ["extractor.ts"],
+    srcs = ["extractor.mts"],
     data = ["//:node_modules/node-html-parser"],
     deps = [
         "//common:prerender_annotation_walker",
@@ -58,7 +58,7 @@ ts_project(
 
 ts_project(
     name = "extractor_test_lib",
-    srcs = ["extractor_test.ts"],
+    srcs = ["extractor_test.mts"],
     testonly = True,
     deps = [
         ":extractor",
@@ -74,7 +74,7 @@ jasmine_node_test(
 
 ts_project(
     name = "metadata",
-    srcs = ["metadata.ts"],
+    srcs = ["metadata.mts"],
     deps = [
         "//common/models:prerender_annotation",
         "//common/models:prerender_metadata",
@@ -83,7 +83,7 @@ ts_project(
 
 ts_project(
     name = "metadata_test_lib",
-    srcs = ["metadata_test.ts"],
+    srcs = ["metadata_test.mts"],
     testonly = True,
     deps = [
         ":metadata",
diff --git a/tools/binaries/annotation_extractor/annotation_extractor.ts b/tools/binaries/annotation_extractor/annotation_extractor.mts
similarity index 93%
rename from tools/binaries/annotation_extractor/annotation_extractor.ts
rename to tools/binaries/annotation_extractor/annotation_extractor.mts
index 0dd5c029..738f1197 100644
--- a/tools/binaries/annotation_extractor/annotation_extractor.ts
+++ b/tools/binaries/annotation_extractor/annotation_extractor.mts
@@ -1,13 +1,13 @@
 import { promises as fs } from 'fs';
 import yargs from 'yargs';
 import * as path from 'path';
-import { main } from '../../../common/binary';
-import { mdSpacing } from '../../../common/formatters';
-import { extract } from './extractor';
-import { metadataFromPrerenderAnnotations } from './metadata';
-import { annotationsEqual } from '../../../common/models/prerender_annotation';
-import { unique } from '../../../common/collections';
-import { PrerenderMetadata } from 'common/models/prerender_metadata';
+import { main } from '../../../common/binary.mjs';
+import { mdSpacing } from '../../../common/formatters.mjs';
+import { extract } from './extractor.mjs';
+import { metadataFromPrerenderAnnotations } from './metadata.mjs';
+import { annotationsEqual } from '../../../common/models/prerender_annotation.mjs';
+import { unique } from '../../../common/collections.mjs';
+import { PrerenderMetadata } from '../../../common/models/prerender_metadata.mjs';
 
 main(async () => {
     const {
diff --git a/tools/binaries/annotation_extractor/annotation_extractor_test.ts b/tools/binaries/annotation_extractor/annotation_extractor_test.mts
similarity index 97%
rename from tools/binaries/annotation_extractor/annotation_extractor_test.ts
rename to tools/binaries/annotation_extractor/annotation_extractor_test.mts
index 7c4d2ffa..6dbdcbe2 100644
--- a/tools/binaries/annotation_extractor/annotation_extractor_test.ts
+++ b/tools/binaries/annotation_extractor/annotation_extractor_test.mts
@@ -1,9 +1,9 @@
 import { promises as fs } from 'fs';
-import { mockPrerenderMetadata, mockScriptMetadata } from '../../../common/models/prerender_metadata_mock';
-import { PrerenderMetadata } from '../../../common/models/prerender_metadata';
-import { execBinary, ProcessResult } from '../../../common/testing/binary';
-import { useTempDir } from '../../../common/testing/temp_dir';
-import { createAnnotation } from '../../../common/models/prerender_annotation';
+import { mockPrerenderMetadata, mockScriptMetadata } from '../../../common/models/prerender_metadata_mock.mjs';
+import { PrerenderMetadata } from '../../../common/models/prerender_metadata.mjs';
+import { execBinary, ProcessResult } from '../../../common/testing/binary.mjs';
+import { useTempDir } from '../../../common/testing/temp_dir.mjs';
+import { createAnnotation } from '../../../common/models/prerender_annotation.mjs';
 
 const extractor = 'tools/binaries/annotation_extractor/annotation_extractor.sh';
 
diff --git a/tools/binaries/annotation_extractor/extractor.ts b/tools/binaries/annotation_extractor/extractor.mts
similarity index 97%
rename from tools/binaries/annotation_extractor/extractor.ts
rename to tools/binaries/annotation_extractor/extractor.mts
index 9bb182bd..47732a53 100644
--- a/tools/binaries/annotation_extractor/extractor.ts
+++ b/tools/binaries/annotation_extractor/extractor.mts
@@ -1,6 +1,6 @@
 import { parse, HTMLElement } from 'node-html-parser';
-import { PrerenderAnnotation } from '../../../common/models/prerender_annotation';
-import { walkAllAnnotations } from '../../../common/prerender_annotation_walker';
+import { PrerenderAnnotation } from '../../../common/models/prerender_annotation.mjs';
+import { walkAllAnnotations } from '../../../common/prerender_annotation_walker.mjs';
 
 /**
  * Parses the given string as HTML and return a tuple of the input HTML with
diff --git a/tools/binaries/annotation_extractor/extractor_test.ts b/tools/binaries/annotation_extractor/extractor_test.mts
similarity index 98%
rename from tools/binaries/annotation_extractor/extractor_test.ts
rename to tools/binaries/annotation_extractor/extractor_test.mts
index 259c7f78..b5d08ea6 100644
--- a/tools/binaries/annotation_extractor/extractor_test.ts
+++ b/tools/binaries/annotation_extractor/extractor_test.mts
@@ -1,5 +1,5 @@
-import { extract } from './extractor';
-import { createAnnotation } from '../../../common/models/prerender_annotation';
+import { extract } from './extractor.mjs';
+import { createAnnotation } from '../../../common/models/prerender_annotation.mjs';
 
 describe('extractor', () => {
     describe('extract()', () => {
diff --git a/tools/binaries/annotation_extractor/metadata.ts b/tools/binaries/annotation_extractor/metadata.mts
similarity index 96%
rename from tools/binaries/annotation_extractor/metadata.ts
rename to tools/binaries/annotation_extractor/metadata.mts
index 36fb6067..80b5baf8 100644
--- a/tools/binaries/annotation_extractor/metadata.ts
+++ b/tools/binaries/annotation_extractor/metadata.mts
@@ -1,5 +1,5 @@
-import { PrerenderAnnotation } from '../../../common/models/prerender_annotation';
-import { ScriptMetadata } from '../../../common/models/prerender_metadata';
+import { PrerenderAnnotation } from '../../../common/models/prerender_annotation.mjs';
+import { ScriptMetadata } from '../../../common/models/prerender_metadata.mjs';
 
 /**
  * Converts a set of {@link PrerenderAnnotation} objects into a list of
diff --git a/tools/binaries/annotation_extractor/metadata_test.ts b/tools/binaries/annotation_extractor/metadata_test.mts
similarity index 88%
rename from tools/binaries/annotation_extractor/metadata_test.ts
rename to tools/binaries/annotation_extractor/metadata_test.mts
index 3f815d75..f77f3798 100644
--- a/tools/binaries/annotation_extractor/metadata_test.ts
+++ b/tools/binaries/annotation_extractor/metadata_test.mts
@@ -1,6 +1,6 @@
-import { mockScriptAnnotation, mockStyleAnnotation } from '../../../common/models/prerender_annotation_mock';
-import { mockScriptMetadata } from '../../../common/models/prerender_metadata_mock';
-import { metadataFromPrerenderAnnotations } from './metadata';
+import { mockScriptAnnotation, mockStyleAnnotation } from '../../../common/models/prerender_annotation_mock.mjs';
+import { mockScriptMetadata } from '../../../common/models/prerender_metadata_mock.mjs';
+import { metadataFromPrerenderAnnotations } from './metadata.mjs';
 
 describe('metadata', () => {
     describe('metadataFromPrerenderAnnotations()', () => {
diff --git a/tools/binaries/css_bundler/BUILD.bazel b/tools/binaries/css_bundler/BUILD.bazel
index fabfcf7b..075fe99a 100644
--- a/tools/binaries/css_bundler/BUILD.bazel
+++ b/tools/binaries/css_bundler/BUILD.bazel
@@ -11,14 +11,14 @@ bzl_library(
 
 js_binary(
     name = "css_bundler",
-    entry_point = "css_bundler.js",
+    entry_point = "css_bundler.mjs",
     data = [":css_bundler_lib"],
     visibility = ["//visibility:public"],
 )
 
 ts_project(
     name = "css_bundler_lib",
-    srcs = ["css_bundler.ts"],
+    srcs = ["css_bundler.mts"],
     data = ["//:node_modules/yargs"],
     deps = [
         "//common:binary",
@@ -31,7 +31,7 @@ ts_project(
 
 ts_project(
     name = "css_bundler_test_lib",
-    srcs = ["css_bundler_test.ts"],
+    srcs = ["css_bundler_test.mts"],
     testonly = True,
     deps = [
         "//common/testing:binary",
diff --git a/tools/binaries/css_bundler/css_bundler.ts b/tools/binaries/css_bundler/css_bundler.mts
similarity index 95%
rename from tools/binaries/css_bundler/css_bundler.ts
rename to tools/binaries/css_bundler/css_bundler.mts
index fa8aef49..d4113935 100644
--- a/tools/binaries/css_bundler/css_bundler.ts
+++ b/tools/binaries/css_bundler/css_bundler.mts
@@ -1,8 +1,8 @@
 import { promises as fs } from 'fs';
 import { bundleAsync } from 'lightningcss';
 import yargs from 'yargs';
-import { main } from '../../../common/binary';
-import { mdSpacing } from '../../../common/formatters';
+import { main } from '../../../common/binary.mjs';
+import { mdSpacing } from '../../../common/formatters.mjs';
 
 main(async () => {
     const {
diff --git a/tools/binaries/css_bundler/css_bundler_test.ts b/tools/binaries/css_bundler/css_bundler_test.mts
similarity index 97%
rename from tools/binaries/css_bundler/css_bundler_test.ts
rename to tools/binaries/css_bundler/css_bundler_test.mts
index 4b634650..484af5a7 100644
--- a/tools/binaries/css_bundler/css_bundler_test.ts
+++ b/tools/binaries/css_bundler/css_bundler_test.mts
@@ -1,6 +1,6 @@
 import { promises as fs } from 'fs';
-import { useTempDir } from '../../../common/testing/temp_dir';
-import { execBinary, ProcessResult } from '../../../common/testing/binary';
+import { useTempDir } from '../../../common/testing/temp_dir.mjs';
+import { execBinary, ProcessResult } from '../../../common/testing/binary.mjs';
 
 const binary = 'tools/binaries/css_bundler/css_bundler.sh';
 
diff --git a/tools/binaries/renderer/BUILD.bazel b/tools/binaries/renderer/BUILD.bazel
index 393dedfe..3b371017 100644
--- a/tools/binaries/renderer/BUILD.bazel
+++ b/tools/binaries/renderer/BUILD.bazel
@@ -5,7 +5,7 @@ load(":build_vars.bzl", "RENDERER_RUNTIME_DEPS")
 
 ts_project(
     name = "renderer",
-    srcs = ["renderer.ts"],
+    srcs = ["renderer.mts"],
     visibility = ["//visibility:public"],
     deps = [
         ":entry_point",
@@ -19,7 +19,7 @@ ts_project(
 
 ts_project(
     name = "renderer_test_lib",
-    srcs = ["renderer_test.ts"],
+    srcs = ["renderer_test.mts"],
     testonly = True,
     deps = [
         ":renderer",
@@ -39,7 +39,7 @@ jasmine_node_test(
 
 ts_project(
     name = "entry_point",
-    srcs = ["entry_point.ts"],
+    srcs = ["entry_point.mts"],
     deps = [
         "//common:probably",
         "//common/models:prerender_resource",
@@ -48,7 +48,7 @@ ts_project(
 
 ts_project(
     name = "entry_point_test_lib",
-    srcs = ["entry_point_test.ts"],
+    srcs = ["entry_point_test.mts"],
     deps = [
         ":entry_point",
         "//common:probably",
diff --git a/tools/binaries/renderer/entry_point.ts b/tools/binaries/renderer/entry_point.mts
similarity index 97%
rename from tools/binaries/renderer/entry_point.ts
rename to tools/binaries/renderer/entry_point.mts
index 02fa9700..a7087472 100644
--- a/tools/binaries/renderer/entry_point.ts
+++ b/tools/binaries/renderer/entry_point.mts
@@ -1,5 +1,5 @@
-import { PrerenderResource } from '../../../common/models/prerender_resource';
-import { Probably } from '../../../common/probably';
+import { PrerenderResource } from '../../../common/models/prerender_resource.mjs';
+import { Probably } from '../../../common/probably.mjs';
 
 /**
  * Invokes the default function export of the given CommonJS module, and validates the
diff --git a/tools/binaries/renderer/entry_point_test.ts b/tools/binaries/renderer/entry_point_test.mts
similarity index 97%
rename from tools/binaries/renderer/entry_point_test.ts
rename to tools/binaries/renderer/entry_point_test.mts
index c3b9e7ba..622a0c58 100644
--- a/tools/binaries/renderer/entry_point_test.ts
+++ b/tools/binaries/renderer/entry_point_test.mts
@@ -1,6 +1,6 @@
-import { PrerenderResource } from '../../../common/models/prerender_resource';
-import { Probably } from '../../../common/probably';
-import { invoke } from './entry_point';
+import { PrerenderResource } from '../../../common/models/prerender_resource.mjs';
+import { Probably } from '../../../common/probably.mjs';
+import { invoke } from './entry_point.mjs';
 
 function definitelyIterable<T>(probably: Iterable<Probably<T>> | AsyncIterable<Probably<T>>): Iterable<T> | AsyncIterable<T> {
     return probably as unknown as Iterable<T> | AsyncIterable<T>;
diff --git a/tools/binaries/renderer/renderer.ts b/tools/binaries/renderer/renderer.mts
similarity index 97%
rename from tools/binaries/renderer/renderer.ts
rename to tools/binaries/renderer/renderer.mts
index 90e58bb5..7144d9b7 100644
--- a/tools/binaries/renderer/renderer.ts
+++ b/tools/binaries/renderer/renderer.mts
@@ -1,9 +1,9 @@
 import { promises as fs } from 'fs';
 import * as path from 'path';
 import yargs from 'yargs';
-import type { MainFn } from '../../../common/binary';
-import { mdSpacing } from '../../../common/formatters';
-import { invoke } from './entry_point';
+import type { MainFn } from '../../../common/binary.mjs';
+import { mdSpacing } from '../../../common/formatters.mjs';
+import { invoke } from './entry_point.mjs';
 
 // Cannot include a value reference of `rules_prerender` because the user will
 // depend on it via the `npm_link_package()` in their own workspace, not the
diff --git a/tools/binaries/renderer/renderer_test.ts b/tools/binaries/renderer/renderer_test.mts
similarity index 97%
rename from tools/binaries/renderer/renderer_test.ts
rename to tools/binaries/renderer/renderer_test.mts
index 23930fd7..f39434a5 100644
--- a/tools/binaries/renderer/renderer_test.ts
+++ b/tools/binaries/renderer/renderer_test.mts
@@ -1,9 +1,9 @@
 import { promises as fs } from 'fs';
 import * as rulesPrerender from 'rules_prerender';
-import { ProcessResult } from '../../../common/testing/binary';
-import { useTempDir } from '../../../common/testing/temp_dir';
-import { createAnnotation } from '../../../common/models/prerender_annotation';
-import { createRenderer } from './renderer';
+import { ProcessResult } from '../../../common/testing/binary.mjs';
+import { useTempDir } from '../../../common/testing/temp_dir.mjs';
+import { createAnnotation } from '../../../common/models/prerender_annotation.mjs';
+import { createRenderer } from './renderer.mjs';
 
 /**
  * Invokes the renderer binary. We invoke this in-process instead of spinning up a
diff --git a/tools/binaries/resource_injector/BUILD.bazel b/tools/binaries/resource_injector/BUILD.bazel
index 095e14f7..b1f56433 100644
--- a/tools/binaries/resource_injector/BUILD.bazel
+++ b/tools/binaries/resource_injector/BUILD.bazel
@@ -4,14 +4,14 @@ load("//tools/typescript:defs.bzl", "ts_project")
 
 js_binary(
     name = "resource_injector",
-    entry_point = "resource_injector.js",
+    entry_point = "resource_injector.mjs",
     visibility = ["//visibility:public"],
     data = [":resource_injector_lib"],
 )
 
 ts_project(
     name = "resource_injector_lib",
-    srcs = ["resource_injector.ts"],
+    srcs = ["resource_injector.mts"],
     data = ["//:node_modules/yargs"],
     deps = [
         ":config",
@@ -25,7 +25,7 @@ ts_project(
 
 ts_project(
     name = "resource_injector_test_lib",
-    srcs = ["resource_injector_test.ts"],
+    srcs = ["resource_injector_test.mts"],
     testonly = True,
     deps = [
         ":config",
@@ -44,12 +44,12 @@ jasmine_node_test(
 
 ts_project(
     name = "config",
-    srcs = ["config.ts"],
+    srcs = ["config.mts"],
 )
 
 ts_project(
     name = "injector",
-    srcs = ["injector.ts"],
+    srcs = ["injector.mts"],
     data = ["//:node_modules/node-html-parser"],
     deps = [
         ":config",
@@ -60,7 +60,7 @@ ts_project(
 
 ts_project(
     name = "injector_test_lib",
-    srcs = ["injector_test.ts"],
+    srcs = ["injector_test.mts"],
     testonly = True,
     deps = [
         ":config",
diff --git a/tools/binaries/resource_injector/config.ts b/tools/binaries/resource_injector/config.mts
similarity index 100%
rename from tools/binaries/resource_injector/config.ts
rename to tools/binaries/resource_injector/config.mts
diff --git a/tools/binaries/resource_injector/injector.ts b/tools/binaries/resource_injector/injector.mts
similarity index 96%
rename from tools/binaries/resource_injector/injector.ts
rename to tools/binaries/resource_injector/injector.mts
index a815243c..981f6a61 100644
--- a/tools/binaries/resource_injector/injector.ts
+++ b/tools/binaries/resource_injector/injector.mts
@@ -1,7 +1,7 @@
 import { HTMLElement, parse } from 'node-html-parser';
-import { InjectorConfig, InjectScript } from './config';
-import { AnnotationNode, walkAllAnnotations } from '../../../common/prerender_annotation_walker';
-import { FileSystem, diskFs } from '../../../common/file_system';
+import { InjectorConfig, InjectScript } from './config.mjs';
+import { AnnotationNode, walkAllAnnotations } from '../../../common/prerender_annotation_walker.mjs';
+import { FileSystem, diskFs } from '../../../common/file_system.mjs';
 
 /**
  * Parses the given HTML document and injects all the resources specified by the
diff --git a/tools/binaries/resource_injector/injector_test.ts b/tools/binaries/resource_injector/injector_test.mts
similarity index 97%
rename from tools/binaries/resource_injector/injector_test.ts
rename to tools/binaries/resource_injector/injector_test.mts
index 27e186ca..e0850b3e 100644
--- a/tools/binaries/resource_injector/injector_test.ts
+++ b/tools/binaries/resource_injector/injector_test.mts
@@ -1,7 +1,7 @@
-import { FileSystemFake } from '../../../common/file_system_fake';
-import { createAnnotation } from '../../../common/models/prerender_annotation';
-import { InjectorConfig } from './config';
-import { inject } from './injector';
+import { FileSystemFake } from '../../../common/file_system_fake.mjs';
+import { createAnnotation } from '../../../common/models/prerender_annotation.mjs';
+import { InjectorConfig } from './config.mjs';
+import { inject } from './injector.mjs';
 
 describe('injector', () => {
     describe('inject()', () => {
diff --git a/tools/binaries/resource_injector/resource_injector.ts b/tools/binaries/resource_injector/resource_injector.mts
similarity index 97%
rename from tools/binaries/resource_injector/resource_injector.ts
rename to tools/binaries/resource_injector/resource_injector.mts
index 0580623c..3239ce6c 100644
--- a/tools/binaries/resource_injector/resource_injector.ts
+++ b/tools/binaries/resource_injector/resource_injector.mts
@@ -1,10 +1,10 @@
 import { promises as fs } from 'fs';
 import * as path from 'path';
 import yargs from 'yargs';
-import { main } from '../../../common/binary';
-import { mdSpacing } from '../../../common/formatters';
-import { InjectorConfig } from './config';
-import { inject } from './injector';
+import { main } from '../../../common/binary.mjs';
+import { mdSpacing } from '../../../common/formatters.mjs';
+import { InjectorConfig } from './config.mjs';
+import { inject } from './injector.mjs';
 
 main(async () => {
     // Define command line flags.
diff --git a/tools/binaries/resource_injector/resource_injector_test.ts b/tools/binaries/resource_injector/resource_injector_test.mts
similarity index 98%
rename from tools/binaries/resource_injector/resource_injector_test.ts
rename to tools/binaries/resource_injector/resource_injector_test.mts
index f5a66ffc..a01df031 100644
--- a/tools/binaries/resource_injector/resource_injector_test.ts
+++ b/tools/binaries/resource_injector/resource_injector_test.mts
@@ -1,7 +1,7 @@
 import { promises as fs } from 'fs';
-import { InjectorConfig } from './config';
-import { execBinary, ProcessResult } from '../../../common/testing/binary';
-import { useTempDir } from '../../../common/testing/temp_dir';
+import { InjectorConfig } from './config.mjs';
+import { execBinary, ProcessResult } from '../../../common/testing/binary.mjs';
+import { useTempDir } from '../../../common/testing/temp_dir.mjs';
 
 const injector = 'tools/binaries/resource_injector/resource_injector.sh';
 
diff --git a/tools/binaries/resource_packager/BUILD.bazel b/tools/binaries/resource_packager/BUILD.bazel
index 3f4b54cf..3d40ef6d 100644
--- a/tools/binaries/resource_packager/BUILD.bazel
+++ b/tools/binaries/resource_packager/BUILD.bazel
@@ -4,14 +4,14 @@ load("//tools/typescript:defs.bzl", "ts_project")
 
 js_binary(
     name = "resource_packager",
-    entry_point = ":resource_packager.js",
+    entry_point = ":resource_packager.mjs",
     visibility = ["//visibility:public"],
     data = [":resource_packager_lib"],
 )
 
 ts_project(
     name = "resource_packager_lib",
-    srcs = ["resource_packager.ts"],
+    srcs = ["resource_packager.mts"],
     data = ["//:node_modules/yargs"],
     deps = [
         ":package_loader",
@@ -25,7 +25,7 @@ ts_project(
 
 ts_project(
     name = "resource_packager_test_lib",
-    srcs = ["resource_packager_test.ts"],
+    srcs = ["resource_packager_test.mts"],
     testonly = True,
     deps = [
         "//common/testing:binary",
@@ -43,7 +43,7 @@ jasmine_node_test(
 
 ts_project(
     name = "package_loader",
-    srcs = ["package_loader.ts"],
+    srcs = ["package_loader.mts"],
     deps = [
         ":resource_map",
         "//:node_modules/@types/node",
@@ -52,7 +52,7 @@ ts_project(
 
 ts_project(
     name = "package_loader_test_lib",
-    srcs = ["package_loader_test.ts"],
+    srcs = ["package_loader_test.mts"],
     testonly = True,
     deps = [
         ":package_loader",
@@ -69,7 +69,7 @@ jasmine_node_test(
 
 ts_project(
     name = "packager",
-    srcs = ["packager.ts"],
+    srcs = ["packager.mts"],
     deps = [
         ":resource_map",
         "//common:file_system",
@@ -78,7 +78,7 @@ ts_project(
 
 ts_project(
     name = "packager_test_lib",
-    srcs = ["packager_test.ts"],
+    srcs = ["packager_test.mts"],
     testonly = True,
     deps = [
         ":packager",
@@ -96,12 +96,12 @@ jasmine_node_test(
 
 ts_project(
     name = "resource_map",
-    srcs = ["resource_map.ts"],
+    srcs = ["resource_map.mts"],
 )
 
 ts_project(
     name = "resource_map_test_lib",
-    srcs = ["resource_map_test.ts"],
+    srcs = ["resource_map_test.mts"],
     testonly = True,
     deps = [
         ":resource_map",
@@ -117,7 +117,7 @@ jasmine_node_test(
 
 ts_project(
     name = "resource_map_mock",
-    srcs = ["resource_map_mock.ts"],
+    srcs = ["resource_map_mock.mts"],
     testonly = True,
     deps = [
         ":resource_map",
diff --git a/tools/binaries/resource_packager/package_loader.ts b/tools/binaries/resource_packager/package_loader.mts
similarity index 96%
rename from tools/binaries/resource_packager/package_loader.ts
rename to tools/binaries/resource_packager/package_loader.mts
index df03a6df..485cd2f4 100644
--- a/tools/binaries/resource_packager/package_loader.ts
+++ b/tools/binaries/resource_packager/package_loader.mts
@@ -1,5 +1,5 @@
 import { promises as fs } from 'fs';
-import { ResourceMap } from './resource_map';
+import { ResourceMap } from './resource_map.mjs';
 
 /**
  * Loads the given directory and returns a {@link ResourceMap} of all its
diff --git a/tools/binaries/resource_packager/package_loader_test.ts b/tools/binaries/resource_packager/package_loader_test.mts
similarity index 88%
rename from tools/binaries/resource_packager/package_loader_test.ts
rename to tools/binaries/resource_packager/package_loader_test.mts
index 83438677..993ff378 100644
--- a/tools/binaries/resource_packager/package_loader_test.ts
+++ b/tools/binaries/resource_packager/package_loader_test.mts
@@ -1,5 +1,5 @@
-import { loadPackage } from './package_loader';
-import { useTempDir } from '../../../common/testing/temp_dir';
+import { loadPackage } from './package_loader.mjs';
+import { useTempDir } from '../../../common/testing/temp_dir.mjs';
 import { promises as fs } from 'fs';
 
 describe('package_loader', () => {
diff --git a/tools/binaries/resource_packager/packager.ts b/tools/binaries/resource_packager/packager.mts
similarity index 93%
rename from tools/binaries/resource_packager/packager.ts
rename to tools/binaries/resource_packager/packager.mts
index 5260b338..eb3af917 100644
--- a/tools/binaries/resource_packager/packager.ts
+++ b/tools/binaries/resource_packager/packager.mts
@@ -1,5 +1,5 @@
-import { diskFs, FileSystem } from '../../../common/file_system';
-import { ResourceMap } from './resource_map';
+import { diskFs, FileSystem } from '../../../common/file_system.mjs';
+import { ResourceMap } from './resource_map.mjs';
 
 /**
  * Copies all the provided resources to their specified URL path under the given
diff --git a/tools/binaries/resource_packager/packager_test.ts b/tools/binaries/resource_packager/packager_test.mts
similarity index 95%
rename from tools/binaries/resource_packager/packager_test.ts
rename to tools/binaries/resource_packager/packager_test.mts
index c2e4c252..683e457f 100644
--- a/tools/binaries/resource_packager/packager_test.ts
+++ b/tools/binaries/resource_packager/packager_test.mts
@@ -1,7 +1,7 @@
-import { FileSystemFake } from '../../../common/file_system_fake';
-import { pack } from './packager';
-import { ResourceMap } from './resource_map';
-import { mockFileRef } from './resource_map_mock';
+import { FileSystemFake } from '../../../common/file_system_fake.mjs';
+import { pack } from './packager.mjs';
+import { ResourceMap } from './resource_map.mjs';
+import { mockFileRef } from './resource_map_mock.mjs';
 
 describe('packager', () => {
     describe('pack()', () => {
diff --git a/tools/binaries/resource_packager/resource_map.ts b/tools/binaries/resource_packager/resource_map.mts
similarity index 100%
rename from tools/binaries/resource_packager/resource_map.ts
rename to tools/binaries/resource_packager/resource_map.mts
diff --git a/tools/binaries/resource_packager/resource_map_mock.ts b/tools/binaries/resource_packager/resource_map_mock.mts
similarity index 90%
rename from tools/binaries/resource_packager/resource_map_mock.ts
rename to tools/binaries/resource_packager/resource_map_mock.mts
index 780b1ad4..2125d456 100644
--- a/tools/binaries/resource_packager/resource_map_mock.ts
+++ b/tools/binaries/resource_packager/resource_map_mock.mts
@@ -3,8 +3,8 @@
  * @see /README.md#Mocking
  */
 
-import { UrlPath, FileRef, ResourceMap } from './resource_map';
-import { Public, unmockedFunc } from '../../../common/testing/mocks';
+import { UrlPath, FileRef, ResourceMap } from './resource_map.mjs';
+import { Public, unmockedFunc } from '../../../common/testing/mocks.mjs';
 
 /** Mocks a {@link ResourceMap} object with the given property overrides. */
 export function mockResourceMap(overrides: Partial<ResourceMap> = {}):
diff --git a/tools/binaries/resource_packager/resource_map_test.ts b/tools/binaries/resource_packager/resource_map_test.mts
similarity index 97%
rename from tools/binaries/resource_packager/resource_map_test.ts
rename to tools/binaries/resource_packager/resource_map_test.mts
index 896e0d20..410fda1b 100644
--- a/tools/binaries/resource_packager/resource_map_test.ts
+++ b/tools/binaries/resource_packager/resource_map_test.mts
@@ -1,5 +1,5 @@
-import { ResourceMap } from './resource_map';
-import { mockFileRef } from './resource_map_mock';
+import { ResourceMap } from './resource_map.mjs';
+import { mockFileRef } from './resource_map_mock.mjs';
 
 describe('ResourceMap', () => {
     describe('urlPaths()', () => {
diff --git a/tools/binaries/resource_packager/resource_packager.ts b/tools/binaries/resource_packager/resource_packager.mts
similarity index 94%
rename from tools/binaries/resource_packager/resource_packager.ts
rename to tools/binaries/resource_packager/resource_packager.mts
index bb56658a..8b78cf8f 100644
--- a/tools/binaries/resource_packager/resource_packager.ts
+++ b/tools/binaries/resource_packager/resource_packager.mts
@@ -1,9 +1,9 @@
 import yargs from 'yargs';
-import { main } from '../../../common/binary';
-import { mdSpacing } from '../../../common/formatters';
-import { pack } from './packager';
-import { ResourceMap } from './resource_map';
-import { loadPackage } from './package_loader';
+import { main } from '../../../common/binary.mjs';
+import { mdSpacing } from '../../../common/formatters.mjs';
+import { pack } from './packager.mjs';
+import { ResourceMap } from './resource_map.mjs';
+import { loadPackage } from './package_loader.mjs';
 
 main(async (args) => {
     const {
diff --git a/tools/binaries/resource_packager/resource_packager_test.ts b/tools/binaries/resource_packager/resource_packager_test.mts
similarity index 98%
rename from tools/binaries/resource_packager/resource_packager_test.ts
rename to tools/binaries/resource_packager/resource_packager_test.mts
index 66b4fc09..f0fb4a7f 100644
--- a/tools/binaries/resource_packager/resource_packager_test.ts
+++ b/tools/binaries/resource_packager/resource_packager_test.mts
@@ -1,6 +1,6 @@
 import { promises as fs } from 'fs';
-import { useTempDir } from '../../../common/testing/temp_dir';
-import { ProcessResult, execBinary } from '../../../common/testing/binary';
+import { useTempDir } from '../../../common/testing/temp_dir.mjs';
+import { ProcessResult, execBinary } from '../../../common/testing/binary.mjs';
 
 const binary = 'tools/binaries/resource_packager/resource_packager.sh';
 
diff --git a/tools/binaries/script_entry_generator/BUILD.bazel b/tools/binaries/script_entry_generator/BUILD.bazel
index 210894c9..59cb52e9 100644
--- a/tools/binaries/script_entry_generator/BUILD.bazel
+++ b/tools/binaries/script_entry_generator/BUILD.bazel
@@ -4,14 +4,14 @@ load("//tools/typescript:defs.bzl", "ts_project")
 
 js_binary(
     name = "script_entry_generator",
-    entry_point = ":script_entry_generator.js",
+    entry_point = ":script_entry_generator.mjs",
     visibility = ["//visibility:public"],
     data = [":script_entry_generator_lib"],
 )
 
 ts_project(
     name = "script_entry_generator_lib",
-    srcs = ["script_entry_generator.ts"],
+    srcs = ["script_entry_generator.mts"],
     data = ["//:node_modules/yargs"],
     deps = [
         ":generator",
@@ -25,7 +25,7 @@ ts_project(
 
 ts_project(
     name = "script_entry_generator_test_lib",
-    srcs = ["script_entry_generator_test.ts"],
+    srcs = ["script_entry_generator_test.mts"],
     testonly = True,
     deps = [
         "//common/models:prerender_metadata_mock",
@@ -44,13 +44,13 @@ jasmine_node_test(
 
 ts_project(
     name = "generator",
-    srcs = ["generator.ts"],
+    srcs = ["generator.mts"],
     deps = ["//common/models:prerender_metadata"],
 )
 
 ts_project(
     name = "generator_test_lib",
-    srcs = ["generator_test.ts"],
+    srcs = ["generator_test.mts"],
     testonly = True,
     deps = [
         ":generator",
diff --git a/tools/binaries/script_entry_generator/generator.ts b/tools/binaries/script_entry_generator/generator.mts
similarity index 98%
rename from tools/binaries/script_entry_generator/generator.ts
rename to tools/binaries/script_entry_generator/generator.mts
index e807eee0..9831196a 100644
--- a/tools/binaries/script_entry_generator/generator.ts
+++ b/tools/binaries/script_entry_generator/generator.mts
@@ -1,4 +1,4 @@
-import { ScriptMetadata } from '../../../common/models/prerender_metadata';
+import { ScriptMetadata } from '../../../common/models/prerender_metadata.mjs';
 
 /**
  * Generates a TypeScript entry point which imports all the scripts in the given
diff --git a/tools/binaries/script_entry_generator/generator_test.ts b/tools/binaries/script_entry_generator/generator_test.mts
similarity index 93%
rename from tools/binaries/script_entry_generator/generator_test.ts
rename to tools/binaries/script_entry_generator/generator_test.mts
index 311a05f2..84cbeb4f 100644
--- a/tools/binaries/script_entry_generator/generator_test.ts
+++ b/tools/binaries/script_entry_generator/generator_test.mts
@@ -1,5 +1,5 @@
-import { mockScriptMetadata } from '../../../common/models/prerender_metadata_mock';
-import { generateEntryPoint } from './generator';
+import { mockScriptMetadata } from '../../../common/models/prerender_metadata_mock.mjs';
+import { generateEntryPoint } from './generator.mjs';
 
 describe('generator', () => {
     describe('generateEntryPoint()', () => {
diff --git a/tools/binaries/script_entry_generator/script_entry_generator.ts b/tools/binaries/script_entry_generator/script_entry_generator.mts
similarity index 94%
rename from tools/binaries/script_entry_generator/script_entry_generator.ts
rename to tools/binaries/script_entry_generator/script_entry_generator.mts
index 51ff73bb..17287233 100644
--- a/tools/binaries/script_entry_generator/script_entry_generator.ts
+++ b/tools/binaries/script_entry_generator/script_entry_generator.mts
@@ -1,10 +1,10 @@
 import { promises as fs } from 'fs';
 import * as path from 'path';
 import yargs from 'yargs';
-import { main } from '../../../common/binary';
-import { mdSpacing } from '../../../common/formatters';
-import { PrerenderMetadata } from '../../../common/models/prerender_metadata';
-import { generateEntryPoint } from './generator';
+import { main } from '../../../common/binary.mjs';
+import { mdSpacing } from '../../../common/formatters.mjs';
+import { PrerenderMetadata } from '../../../common/models/prerender_metadata.mjs';
+import { generateEntryPoint } from './generator.mjs';
 
 main(async () => {
     // Parse options and flags.
diff --git a/tools/binaries/script_entry_generator/script_entry_generator_test.ts b/tools/binaries/script_entry_generator/script_entry_generator_test.mts
similarity index 96%
rename from tools/binaries/script_entry_generator/script_entry_generator_test.ts
rename to tools/binaries/script_entry_generator/script_entry_generator_test.mts
index eba7997c..cebf18ed 100644
--- a/tools/binaries/script_entry_generator/script_entry_generator_test.ts
+++ b/tools/binaries/script_entry_generator/script_entry_generator_test.mts
@@ -1,7 +1,7 @@
 import { promises as fs } from 'fs';
-import { mockPrerenderMetadata, mockScriptMetadata } from '../../../common/models/prerender_metadata_mock';
-import { execBinary, ProcessResult } from '../../../common/testing/binary';
-import { useTempDir } from '../../../common/testing/temp_dir';
+import { mockPrerenderMetadata, mockScriptMetadata } from '../../../common/models/prerender_metadata_mock.mjs';
+import { execBinary, ProcessResult } from '../../../common/testing/binary.mjs';
+import { useTempDir } from '../../../common/testing/temp_dir.mjs';
 
 const entryGenerator = 'tools/binaries/script_entry_generator/script_entry_generator.sh';
 
diff --git a/tools/jasmine/jasmine_node_test.bzl b/tools/jasmine/jasmine_node_test.bzl
index 7c379871..8f74610c 100644
--- a/tools/jasmine/jasmine_node_test.bzl
+++ b/tools/jasmine/jasmine_node_test.bzl
@@ -26,6 +26,7 @@ def jasmine_node_test(name, deps, data = [], size = "small", **kwargs):
     jasmine_test(
         name = name,
         config = config_file,
+        module = "esm",
         data = data + deps + [
             ":%s" % config_file,
         ],
diff --git a/tsconfig.json b/tsconfig.json
index e290cd9f..bdf5c3ef 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -6,7 +6,7 @@
     /* Basic Options */
     // "incremental": true,                   /* Enable incremental compilation */
     "target": "ES2019",                       /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019', 'ES2020', or 'ESNEXT'. */
-    "module": "commonjs",                     /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */
+    "module": "ES2020",                       /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */
     "lib": ["ES2020", "DOM"],                 /* Specify library files to be included in the compilation. */
     // "allowJs": true,                       /* Allow javascript files to be compiled. */
     // "checkJs": true,                       /* Report errors in .js files. */
@@ -35,7 +35,7 @@
     "noUncheckedIndexedAccess": true,         /* All index signature types (`{ [key: string]: string }`) implicitly return `undefined`. */
 
     /* Module Resolution Options */
-    // "moduleResolution": "node",            /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
+    "moduleResolution": "node",               /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
     "baseUrl": "./",                          /* Base directory to resolve non-absolute module names. */
     "paths": {                                /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
       "rules_prerender": ["packages/rules_prerender"], // Map `rules_prerender` module to its implementation.