diff --git a/carbonmark-api/package.json b/carbonmark-api/package.json
index ced57c9114..0f5ba8ed1d 100644
--- a/carbonmark-api/package.json
+++ b/carbonmark-api/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@klimadao/carbonmark-api",
-  "version": "3.0.0",
+  "version": "4.0.0",
   "description": "An API for exploring Carbonmark project data, prices and activity.",
   "main": "app.ts",
   "scripts": {
diff --git a/carbonmark-api/src/models/Listing.model.ts b/carbonmark-api/src/models/Listing.model.ts
index f8adf7eca0..7409301cc1 100644
--- a/carbonmark-api/src/models/Listing.model.ts
+++ b/carbonmark-api/src/models/Listing.model.ts
@@ -30,10 +30,10 @@ export const ListingModel = Type.Object(
     deleted: Type.Optional(Type.Union([Type.Boolean(), Type.Null()])),
     batches: Nullable(Type.Array(Type.String())),
     batchPrices: Nullable(Type.Array(Type.String())),
-    createdAt: Type.Optional(Type.Union([Type.String(), Type.Null()])),
-    updatedAt: Type.Optional(Type.Union([Type.String(), Type.Null()])),
+    createdAt: Type.Optional(Type.Union([Type.Number(), Type.Null()])),
+    updatedAt: Type.Optional(Type.Union([Type.Number(), Type.Null()])),
     seller: ListingSeller,
-    expiration: Type.String({
+    expiration: Type.Number({
       description: "Unix Timestamp (seconds) when the listing expires.",
     }),
     minFillAmount: Type.String({
diff --git a/carbonmark-api/src/models/User.model.ts b/carbonmark-api/src/models/User.model.ts
index 672567858b..9bcabbeac5 100644
--- a/carbonmark-api/src/models/User.model.ts
+++ b/carbonmark-api/src/models/User.model.ts
@@ -14,9 +14,9 @@ export const UserModel = Type.Object({
   updatedAt: Type.Number(),
   createdAt: Type.Number(),
   wallet: Type.String(),
-  listings: Type.Array(ListingModel),
-  activities: Type.Array(ActivityModel),
-  assets: Type.Array(AssetModel),
+  listings: Type.Optional(Type.Array(ListingModel)),
+  activities: Type.Optional(Type.Array(ActivityModel)),
+  assets: Type.Optional(Type.Array(AssetModel)),
 });
 
 export type User = Static<typeof UserModel>;
diff --git a/carbonmark-api/src/routes/users/get.ts b/carbonmark-api/src/routes/users/get.ts
index baada421c3..3aaf1294ff 100644
--- a/carbonmark-api/src/routes/users/get.ts
+++ b/carbonmark-api/src/routes/users/get.ts
@@ -1,7 +1,7 @@
 import { utils } from "ethers";
 import { FastifyInstance, FastifyReply, FastifyRequest } from "fastify";
+import { User } from "src/models/User.model";
 import { Activity } from "../../models/Activity.model";
-import { User } from "../../models/User.model";
 import {
   getProfileByAddress,
   getProfileByHandle,
diff --git a/carbonmark-api/src/utils/helpers/users.utils.ts b/carbonmark-api/src/utils/helpers/users.utils.ts
index cbe182e182..2e54d814e4 100644
--- a/carbonmark-api/src/utils/helpers/users.utils.ts
+++ b/carbonmark-api/src/utils/helpers/users.utils.ts
@@ -26,7 +26,7 @@ export const getProfileByAddress = async (params: {
 
   if (!doc.exists) return null;
   // eslint-disable-next-line @typescript-eslint/consistent-type-assertions -- known type
-  return doc.data() as UserProfile;
+  return formatProfile(doc.data() as UserProfile);
 };
 
 /**
@@ -56,7 +56,7 @@ export const getUserProfilesByIds = async (params: {
       if (!d.exists) return;
       // eslint-disable-next-line @typescript-eslint/consistent-type-assertions -- known
       const profile = d.data() as UserProfile;
-      UserProfileMap.set(profile.address, profile);
+      UserProfileMap.set(profile.address, formatProfile(profile));
     });
   return UserProfileMap;
 };
@@ -78,5 +78,12 @@ export const getProfileByHandle = async (params: {
   if (snapshot.empty) return null;
   // eslint-disable-next-line @typescript-eslint/consistent-type-assertions -- apply known type
   const profile = snapshot.docs.at(0)?.data() as UserProfile | undefined;
-  return profile || null;
+  return profile ? formatProfile(profile) : null;
+};
+const formatProfile = (profile: UserProfile): UserProfile => {
+  return {
+    ...profile,
+    createdAt: Math.floor(profile.createdAt / 1000),
+    updatedAt: Math.floor(profile.updatedAt / 1000),
+  };
 };
diff --git a/carbonmark-api/src/utils/helpers/utils.ts b/carbonmark-api/src/utils/helpers/utils.ts
index e1870b04b3..501081702f 100644
--- a/carbonmark-api/src/utils/helpers/utils.ts
+++ b/carbonmark-api/src/utils/helpers/utils.ts
@@ -1,5 +1,5 @@
 import { FastifyInstance, FastifyReply } from "fastify";
-import { compact, concat, isArray } from "lodash";
+import { compact, concat, isArray, omit } from "lodash";
 import { filter, flatten, map, pipe, split, trim, uniq } from "lodash/fp";
 import {
   ActivityType,
@@ -230,6 +230,17 @@ export const isMatchingCmsProject = (
   project: CarbonProject
 ) => project?.registryProjectId === projectId && project.registry === registry;
 
+export function formatGraphTimestamps<
+  T extends { createdAt: string | null; updatedAt: string | null },
+>(data: T) {
+  const partialData = omit(data, ["createdAt", "updatedAt"]);
+  return {
+    ...partialData,
+    /** Note: Graph timestamps are in seconds **/
+    createdAt: Number(data.createdAt),
+    updatedAt: Number(data.updatedAt),
+  };
+}
 /**
  * Converts a String into an ActivityType without breaking typescript checks
  */
diff --git a/carbonmark-api/src/utils/marketplace.utils.ts b/carbonmark-api/src/utils/marketplace.utils.ts
index 33a005d168..27e687c572 100644
--- a/carbonmark-api/src/utils/marketplace.utils.ts
+++ b/carbonmark-api/src/utils/marketplace.utils.ts
@@ -5,6 +5,7 @@ import {
 } from "../.generated/types/marketplace.types";
 import { Listing as ListingModel } from "../models/Listing.model";
 import { notNil } from "./functional.utils";
+import { formatGraphTimestamps } from "./helpers/utils";
 
 export const isListingActive = (listing: Partial<Listing>) =>
   notNil(listing.leftToSell) &&
@@ -33,11 +34,12 @@ export type GetProjectListing = NonNullable<
 /** Formats a gql.marketplace listing to match Listing.model, and formats integers */
 export const formatListing = (listing: GetProjectListing): ListingModel => {
   return {
-    ...listing,
+    ...formatGraphTimestamps(listing),
     leftToSell: utils.formatUnits(listing.leftToSell, 18),
     singleUnitPrice: utils.formatUnits(listing.singleUnitPrice, 6),
     minFillAmount: utils.formatUnits(listing.minFillAmount, 18),
     totalAmountToSell: utils.formatUnits(listing.totalAmountToSell, 18),
+    expiration: Number(listing.expiration),
     project: {
       ...listing.project,
       category: listing.project.category?.id || "",
diff --git a/carbonmark-api/test/fixtures/marketplace.ts b/carbonmark-api/test/fixtures/marketplace.ts
index b8d678b66c..c117d3c80c 100644
--- a/carbonmark-api/test/fixtures/marketplace.ts
+++ b/carbonmark-api/test/fixtures/marketplace.ts
@@ -14,6 +14,7 @@ const listing = aListing({
   totalAmountToSell: "100000000000000000000",
   leftToSell: "100000000000000000000",
   updatedAt: "1234",
+  createdAt: "1234",
 });
 
 const projectWithListing = aProject({
diff --git a/carbonmark-api/test/routes/projects/get.test.ts b/carbonmark-api/test/routes/projects/get.test.ts
index b5b32ae2d0..b6b94af9fa 100644
--- a/carbonmark-api/test/routes/projects/get.test.ts
+++ b/carbonmark-api/test/routes/projects/get.test.ts
@@ -201,16 +201,18 @@ describe("GET /projects", () => {
         price: "99",
         updatedAt: marketplace.projectWithListing.listings?.[0].updatedAt,
         listings: [
-          pick(marketplace.projectWithListing.listings![0], [
-            "active",
-            "batchPrices",
-            "batches",
-            "createdAt",
-            "deleted",
-            "updatedAt",
-            "id",
-            "tokenAddress",
-          ]),
+          {
+            ...pick(marketplace.projectWithListing.listings![0], [
+              "active",
+              "batchPrices",
+              "batches",
+              "deleted",
+              "id",
+              "tokenAddress",
+            ]),
+            createdAt: 1234,
+            updatedAt: 1234,
+          },
         ],
         location: {
           geometry: {
diff --git a/carbonmark-api/test/routes/users/get.test.ts b/carbonmark-api/test/routes/users/get.test.ts
index 1c216fb2c9..a81dcc8bce 100644
--- a/carbonmark-api/test/routes/users/get.test.ts
+++ b/carbonmark-api/test/routes/users/get.test.ts
@@ -1,5 +1,4 @@
 import { FastifyInstance } from "fastify";
-import { omit } from "lodash";
 import nock from "nock";
 import {
   aListing,
@@ -7,7 +6,12 @@ import {
 } from "../../../src/.generated/mocks/marketplace.mocks";
 import { GRAPH_URLS } from "../../../src/app.constants";
 import { build } from "../../helper";
-import { DEV_URL, MOCK_ADDRESS, MOCK_USER_PROFILE } from "../../test.constants";
+import {
+  DEV_URL,
+  EXPECTED_USER_RESPONSE,
+  MOCK_ADDRESS,
+  MOCK_USER_PROFILE,
+} from "../../test.constants";
 import { disableAuth, mockFirebase } from "../../test.utils";
 
 describe("GET /users/[walletOrHandle]", () => {
@@ -50,15 +54,8 @@ describe("GET /users/[walletOrHandle]", () => {
     });
     const actual_response = await response.json();
 
-    const expected_response = {
-      ...omit(MOCK_USER_PROFILE, "address"),
-      wallet: MOCK_USER_PROFILE.address,
-      listings: [],
-      activities: [],
-      assets: [],
-    };
     expect(response.statusCode).toBe(200);
-    expect(expected_response).toEqual(actual_response);
+    expect(EXPECTED_USER_RESPONSE).toEqual(actual_response);
   });
 
   test("by handle", async () => {
@@ -66,16 +63,10 @@ describe("GET /users/[walletOrHandle]", () => {
       method: "GET",
       url: `${DEV_URL}/users/${MOCK_USER_PROFILE.handle}`, // use handle instead of wallet address
     });
-    const expected_response = {
-      ...omit(MOCK_USER_PROFILE, "address"),
-      wallet: MOCK_USER_PROFILE.address,
-      listings: [],
-      activities: [],
-      assets: [],
-    };
+
     const actual_response = await response?.json();
     expect(response?.statusCode).toBe(200);
-    expect(actual_response).toEqual(expected_response); // check if the returned handle is correct
+    expect(actual_response).toEqual(EXPECTED_USER_RESPONSE); // check if the returned handle is correct
   });
 
   test("with invalid handle", async () => {
diff --git a/carbonmark-api/test/test.constants.ts b/carbonmark-api/test/test.constants.ts
index 357bdb6171..667742e0cf 100644
--- a/carbonmark-api/test/test.constants.ts
+++ b/carbonmark-api/test/test.constants.ts
@@ -1,3 +1,4 @@
+import { omit } from "lodash";
 import { UserProfile } from "../src/utils/helpers/users.utils";
 
 export const DEV_URL = "http://localhost:3003";
@@ -38,7 +39,17 @@ export const MOCK_USER_PROFILE: UserProfile = {
   createdAt: new Date("1970-01-01T00:00:00Z").getTime(),
   description: "Some description",
   handle: "SomeHandle",
-  updatedAt: Number(new Date()),
+  updatedAt: new Date("2023-11-11T15:05:08Z").getTime(),
   username: "someusername",
   profileImgUrl: null,
 };
+
+export const EXPECTED_USER_RESPONSE = {
+  ...omit(MOCK_USER_PROFILE, ["address", "updatedAt", "createdAt"]),
+  updatedAt: 1699715108,
+  createdAt: 0,
+  wallet: MOCK_USER_PROFILE.address,
+  listings: [],
+  activities: [],
+  assets: [],
+};
diff --git a/package-lock.json b/package-lock.json
index 25f6e6c0ad..ab86246a09 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -589,7 +589,7 @@
     },
     "carbonmark-api": {
       "name": "@klimadao/carbonmark-api",
-      "version": "3.0.0",
+      "version": "4.0.0",
       "license": "ISC",
       "dependencies": {
         "@fastify/autoload": "^5.0.0",