diff --git a/configuration/biome.ts b/configuration/biome.ts
index 869ef86..b514007 100644
--- a/configuration/biome.ts
+++ b/configuration/biome.ts
@@ -1,6 +1,6 @@
 export const templates = {
   recommended: {
-    $schema: 'https://biomejs.dev/schemas/1.6.4/schema.json',
+    $schema: 'node_modules/@biomejs/biome/configuration_schema.json',
     organizeImports: {
       enabled: true,
     },
@@ -10,6 +10,7 @@ export const templates = {
         all: true,
         style: {
           useBlockStatements: 'off',
+          noNamespaceImport: 'off',
         },
       },
     },
diff --git a/configuration/eslint.ts b/configuration/eslint.ts
index 5dbdd12..23aa12e 100644
--- a/configuration/eslint.ts
+++ b/configuration/eslint.ts
@@ -4,6 +4,8 @@ export const templates = {
   },
 }
 
+export const extension = (path: string) => ({ extends: path })
+
 export function createFile(configuration: object) {
-  return { name: 'eslint.config.js', contents: `export default [${configuration}]` }
+  return { name: 'eslint.config.js', contents: `export default [${JSON.stringify(configuration, null, 2)}]` }
 }
diff --git a/configuration/typescript.ts b/configuration/typescript.ts
index 75529d8..921942c 100644
--- a/configuration/typescript.ts
+++ b/configuration/typescript.ts
@@ -6,6 +6,8 @@ export const templates = {
   },
 }
 
+export const extension = (path: string) => ({ extends: path })
+
 export function createFile(configuration: object) {
   return { name: 'tsconfig.json', contents: JSON.stringify(configuration, null, 2) }
 }
diff --git a/index.ts b/index.ts
index 154bbff..9438210 100644
--- a/index.ts
+++ b/index.ts
@@ -11,6 +11,7 @@ import * as playwright from './configuration/playwright'
 import * as prettier from './configuration/prettier'
 import * as typescript from './configuration/typescript'
 import * as vscode from './configuration/vscode'
+import { parse } from './parse'
 import type { Configuration } from './types'
 
 const log = create('zero-configuration', 'blue')
@@ -60,25 +61,10 @@ const userConfiguration = packageJson.configuration ?? moduleContents
 for (const { name, alias, configuration } of configurations) {
   const value = userConfiguration[name] ?? (alias && userConfiguration[alias])
   if (!value) continue
-
-  if (typeof value === 'string' && Object.hasOwn(configuration.templates, value)) {
-    const configurationTemplate = configuration.templates[value as keyof typeof configuration.templates]
-    const file = configuration.createFile(configurationTemplate)
-    await Bun.write(file.name, file.contents)
-    ignores.push(file.name)
-  }
-
-  if (typeof value === 'object') {
-    const file = configuration.createFile(value)
-    await Bun.write(file.name, file.contents)
-    ignores.push(file.name)
-  }
-
-  if (value === true) {
-    const file = configuration.createFile()
-    await Bun.write(file.name, file.contents)
-    ignores.push(file.name)
-  }
+  const file = await parse(value, configuration)
+  if (!file) continue
+  await Bun.write(file.name, file.contents)
+  ignores.push(file.name)
 }
 
 if (ignores.length === 0) {
diff --git a/package.json b/package.json
index 43b88d3..cc8fcf8 100644
--- a/package.json
+++ b/package.json
@@ -16,8 +16,9 @@
     "logua": "^3.0.3"
   },
   "devDependencies": {
-    "@biomejs/biome": "^1.6.4",
-    "@types/bun": "^1.0.12",
+    "@biomejs/biome": "^1.7.0",
+    "@types/bun": "^1.1.0",
+    "eslint-config-airbnb": "^19.0.4",
     "typescript": "^5.4.5"
   },
   "peerDependencies": {
diff --git a/parse.ts b/parse.ts
new file mode 100644
index 0000000..aa0ae20
--- /dev/null
+++ b/parse.ts
@@ -0,0 +1,35 @@
+import { existsSync } from 'node:fs'
+import { join } from 'node:path'
+import { it } from 'avait'
+import type { Configuration } from './types'
+
+const isExtension = async (value: string) => {
+  // NOTE dynamic import in tests will resolve relative to project node_modules and not fixture.
+  const { error } = await it(import(value))
+  if (!error) return true
+  const paths = [value, join(process.cwd(), value), join(process.cwd(), 'node_modules', value)]
+  const fileExists = paths.some(existsSync)
+  if (fileExists) return true
+  return false
+}
+
+export async function parse(value: string | object | boolean, configuration: Configuration['configuration']) {
+  // Template.
+  if (typeof value === 'string' && Object.hasOwn(configuration.templates, value)) {
+    const configurationTemplate = configuration.templates[value as keyof typeof configuration.templates]
+    return configuration.createFile(configurationTemplate)
+  }
+
+  // File extension.
+  if (typeof value === 'string' && (await isExtension(value)) && typeof configuration.extension === 'function') {
+    return configuration.createFile(configuration.extension(value))
+  }
+
+  if (typeof value === 'object') {
+    return configuration.createFile(value)
+  }
+
+  if (value === true) {
+    return configuration.createFile()
+  }
+}
diff --git a/test/basic.test.ts b/test/basic.test.ts
index a5d0e64..ca2f8fa 100644
--- a/test/basic.test.ts
+++ b/test/basic.test.ts
@@ -25,3 +25,15 @@ test('Adds configuration files for basic file setup.', () => {
 
   expect(existsSync(join(fixturePath, 'prettier.config.js'))).toBe(true)
 })
+
+test('Extends existing configurations.', () => {
+  const fixturePath = './test/fixture/extends'
+
+  execSync('bun ./../../../index.ts', {
+    cwd: fixturePath,
+    stdio: 'inherit',
+  })
+
+  expect(existsSync(join(fixturePath, 'eslint.config.js'))).toBe(true)
+  expect(existsSync(join(fixturePath, 'tsconfig.json'))).toBe(true)
+})
diff --git a/test/fixture/extends/package.json b/test/fixture/extends/package.json
new file mode 100644
index 0000000..4f8cfa1
--- /dev/null
+++ b/test/fixture/extends/package.json
@@ -0,0 +1,7 @@
+{
+	"name": "extends",
+	"configuration": {
+		"eslint": "eslint-config-airbnb",
+		"typescript": "my-shared-tsconfig/tsconfig.json"
+	}
+}
diff --git a/test/fixture/file/configuration.ts b/test/fixture/file/configuration.ts
index feb3698..c0d347a 100644
--- a/test/fixture/file/configuration.ts
+++ b/test/fixture/file/configuration.ts
@@ -1,4 +1,4 @@
-import { devices } from '@playwright/test'
+// NOTE imports will fail in fixture.
 
 export const prettier = 'recommended'
 
@@ -8,7 +8,6 @@ export const playwright = {
   projects: [
     {
       name: 'chromium',
-      use: { ...devices['Desktop Chrome'] },
     },
   ],
   webServer: {
diff --git a/types.ts b/types.ts
index 506beda..72517ec 100644
--- a/types.ts
+++ b/types.ts
@@ -7,5 +7,6 @@ export type Configuration = {
     templates: Template
     // biome-ignore lint/suspicious/noExplicitAny: Will be specified in file explicitly.
     createFile: (value?: any) => { name: string; contents: string }
+    extension?: (path: string) => object
   }
 }