diff --git a/packages/sdks/core-js-sdk/src/httpClient/helpers/getClientSessionId.ts b/packages/sdks/core-js-sdk/src/httpClient/helpers/getClientSessionId.ts
new file mode 100644
index 000000000..8aeabf69c
--- /dev/null
+++ b/packages/sdks/core-js-sdk/src/httpClient/helpers/getClientSessionId.ts
@@ -0,0 +1,28 @@
+let sessionId: string;
+
+export const getClientSessionId = (): string => {
+  if (sessionId) {
+    return sessionId;
+  }
+  const currentDate = new Date();
+  const utcString = `${currentDate.getUTCFullYear().toString()}-${(
+    currentDate.getUTCMonth() + 1
+  )
+    .toString()
+    .padStart(2, '0')}-${currentDate
+    .getUTCDate()
+    .toString()
+    .padStart(2, '0')}-${currentDate
+    .getUTCHours()
+    .toString()
+    .padStart(2, '0')}:${currentDate
+    .getUTCMinutes()
+    .toString()
+    .padStart(2, '0')}:${currentDate
+    .getUTCSeconds()
+    .toString()
+    .padStart(2, '0')}:${currentDate.getUTCMilliseconds().toString()}`;
+  const randomSuffix = Math.floor(1000 + Math.random() * 9000);
+  sessionId = `${utcString}-${randomSuffix}`;
+  return sessionId;
+};
diff --git a/packages/sdks/core-js-sdk/src/httpClient/helpers/index.ts b/packages/sdks/core-js-sdk/src/httpClient/helpers/index.ts
index 21de8535e..9bc7ae325 100644
--- a/packages/sdks/core-js-sdk/src/httpClient/helpers/index.ts
+++ b/packages/sdks/core-js-sdk/src/httpClient/helpers/index.ts
@@ -1,4 +1,5 @@
 export { default as createFetchLogger } from './createFetchLogger';
+export { getClientSessionId } from './getClientSessionId';
 
 export function transformSetCookie(setCookieHeader: string) {
   // Split the header by semicolons to separate different attributes
diff --git a/packages/sdks/core-js-sdk/src/httpClient/index.ts b/packages/sdks/core-js-sdk/src/httpClient/index.ts
index 889779812..e7f09db63 100644
--- a/packages/sdks/core-js-sdk/src/httpClient/index.ts
+++ b/packages/sdks/core-js-sdk/src/httpClient/index.ts
@@ -1,4 +1,4 @@
-import { transformSetCookie } from './helpers';
+import { getClientSessionId, transformSetCookie } from './helpers';
 import createFetchLogger from './helpers/createFetchLogger';
 import {
   CreateHttpClientConfig,
@@ -35,6 +35,7 @@ declare const BUILD_VERSION: string;
  */
 const createDescopeHeaders = () => {
   return {
+    'x-descope-sdk-session-id': getClientSessionId(),
     'x-descope-sdk-name': 'core-js',
     'x-descope-sdk-version': BUILD_VERSION,
   };
diff --git a/packages/sdks/core-js-sdk/test/httpClient.test.ts b/packages/sdks/core-js-sdk/test/httpClient.test.ts
index 26c5dc036..c163b981b 100644
--- a/packages/sdks/core-js-sdk/test/httpClient.test.ts
+++ b/packages/sdks/core-js-sdk/test/httpClient.test.ts
@@ -1,5 +1,6 @@
 import { DEFAULT_BASE_API_URL } from '../src/constants';
 import createHttpClient from '../src/httpClient';
+import { getClientSessionId } from '../src/httpClient/helpers';
 import createFetchLogger from '../src/httpClient/helpers/createFetchLogger';
 import { ExtendedResponse } from '../src/httpClient/types';
 
@@ -11,6 +12,7 @@ const afterRequestHook = jest.fn();
 const descopeHeaders = {
   'x-descope-sdk-name': 'core-js',
   'x-descope-sdk-version': globalThis.BUILD_VERSION,
+  'x-descope-sdk-session-id': getClientSessionId(),
 };
 
 const httpClient = createHttpClient({
@@ -160,8 +162,8 @@ describe('httpClient', () => {
           test2: '123',
           test: '123',
           Authorization: 'Bearer 456',
+          ...descopeHeaders,
           'x-descope-sdk-name': 'lulu',
-          'x-descope-sdk-version': globalThis.BUILD_VERSION,
         }),
         method: 'GET',
       },
@@ -205,6 +207,25 @@ describe('httpClient', () => {
       cookiePolicy: null,
     });
 
+    httpClient.get('1/2/3/4', {
+      headers: { test2: '123' },
+      queryParams: { test2: '123' },
+    });
+
+    expect(mockFetch).toHaveBeenCalledWith(
+      'http://descope.com/1/2/3/4?test2=123',
+      {
+        body: undefined,
+        headers: new Headers({
+          test2: '123',
+          test: '123',
+          Authorization: 'Bearer 456',
+          ...descopeHeaders,
+        }),
+        method: 'GET',
+      },
+    );
+
     httpClient.get('1/2/3', {
       headers: { test2: '123' },
       queryParams: { test2: '123' },
diff --git a/packages/sdks/web-js-sdk/test/persistTokens.test.ts b/packages/sdks/web-js-sdk/test/persistTokens.test.ts
index 3cf6e4a31..b3c8272aa 100644
--- a/packages/sdks/web-js-sdk/test/persistTokens.test.ts
+++ b/packages/sdks/web-js-sdk/test/persistTokens.test.ts
@@ -4,9 +4,16 @@ import createSdk from '../src/index';
 import { authInfo } from './mocks';
 import { createMockReturnValue } from './testUtils';
 
+globalThis.Headers = class Headers {
+  constructor(obj: object) {
+    return Object.assign({}, obj);
+  }
+} as any;
+
 const descopeHeaders = {
   'x-descope-sdk-name': 'web-js',
   'x-descope-sdk-version': global.BUILD_VERSION,
+  'x-descope-sdk-session-id': expect.any(String),
 };
 
 const mockFetch = jest.fn().mockReturnValueOnce(new Promise(() => {}));