diff --git a/package.json b/package.json
index 5dee606..ac327ec 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "notificationapi-node-server-sdk",
-  "version": "2.0.1",
+  "version": "2.1.0",
   "description": "NotificationAPI server-side library for Node.js",
   "keywords": [
     "notificationapi",
diff --git a/src/__tests__/notificationapi.test.ts b/src/__tests__/notificationapi.test.ts
index bbae46a..d6c9873 100644
--- a/src/__tests__/notificationapi.test.ts
+++ b/src/__tests__/notificationapi.test.ts
@@ -7,6 +7,7 @@ import {
   Channels,
   CreateSubNotificationRequest,
   DeleteSubNotificationRequest,
+  InAppNotificationPatchRequest,
   PushProviders,
   SendRequest,
   SetUserPreferencesRequest,
@@ -671,6 +672,39 @@ describe('deleteUserPreferences with subNotificationId', () => {
     );
   });
 });
+describe('updateInAppNotification without subNotificationId', () => {
+  const retractEndPointRegex = /.*\/users\/.*/;
+  const clientId = 'testClientId';
+  const clientSecret = 'testClientSecret';
+  const userId = 'testUserId';
+  const hashedUserId = `${createHmac('sha256', clientSecret)
+    .update(userId)
+    .digest('base64')}`;
+  const params: Required<InAppNotificationPatchRequest> = {
+    trackingIds: ['testTrackingId'],
+    opened: '1970-01-01T00:00:00.000Z',
+    clicked: '1970-01-01T00:00:00.000Z',
+    archived: '1970-01-01T00:00:00.000Z',
+    actioned1: '1970-01-01T00:00:00.000Z',
+    actioned2: '1970-01-01T00:00:00.000Z',
+    reply: { date: '1970-01-01T00:00:00.000Z', message: 'nice!' }
+  };
+
+  test('makes API calls to the correct end-point', async () => {
+    axiosMock.onPatch(retractEndPointRegex).reply(200);
+    await notificationapi.init(clientId, clientSecret);
+    await notificationapi.updateInAppNotification(userId, params);
+    expect(axiosMock.history.patch).toHaveLength(1);
+    expect(axiosMock.history.patch[0].url).toEqual(
+      `https://api.notificationapi.com/${clientId}/users/${userId}/notifications/INAPP_WEB`
+    );
+    expect(axiosMock.history.patch[0].params).toEqual(undefined);
+    expect(axiosMock.history.patch[0].headers.Authorization).toEqual(
+      'Basic ' +
+        Buffer.from(`${clientId}:${userId}:${hashedUserId}`).toString('base64')
+    );
+  });
+});
 describe('Identify user', () => {
   const userEndPointRegex = /.*\/users\/.*/;
   const clientId = 'testClientId_identify_user';
diff --git a/src/interfaces.ts b/src/interfaces.ts
index f173a4b..ae4e97a 100644
--- a/src/interfaces.ts
+++ b/src/interfaces.ts
@@ -155,3 +155,15 @@ export interface PushSubscription {
 export interface WebPushToken {
   sub: PushSubscription;
 }
+export interface InAppNotificationPatchRequest {
+  trackingIds: string[];
+  opened?: string;
+  clicked?: string;
+  archived?: string;
+  actioned1?: string;
+  actioned2?: string;
+  reply?: {
+    date: string;
+    message: string;
+  };
+}
diff --git a/src/notificationapi.ts b/src/notificationapi.ts
index d96aa93..3612d6f 100644
--- a/src/notificationapi.ts
+++ b/src/notificationapi.ts
@@ -1,6 +1,7 @@
 import {
   CreateSubNotificationRequest,
   DeleteSubNotificationRequest,
+  InAppNotificationPatchRequest,
   InitConfiguration,
   RetractRequest,
   SendRequest,
@@ -14,7 +15,7 @@ const DEFAULT_BASE_URL = 'https://api.notificationapi.com';
 
 class NotificationAPIService {
   private USER_AGENT = 'notificationapi-node-server-sdk';
-  private VERSION = '2.0.1';
+  private VERSION = '2.1.0';
 
   clientId: null | string = null;
   clientSecret: null | string = null;
@@ -123,7 +124,30 @@ class NotificationAPIService {
         : { notificationId }
     );
   };
-  /** Used to to update a scheduled notification. */
+
+  /** Used to update the opened, archived, ... of an inapp notification. */
+  updateInAppNotification = async (
+    /** The ID of the user in your system. Required.*/
+    userId: string,
+    params: InAppNotificationPatchRequest
+  ) => {
+    const hashedUserId = `${createHmac('sha256', this.clientSecret as string)
+      .update(userId)
+      .digest('base64')}`;
+    const customAuthorization =
+      'Basic ' +
+      Buffer.from(`${this.clientId}:${userId}:${hashedUserId}`).toString(
+        'base64'
+      );
+    return this.request(
+      'PATCH',
+      `users/${userId}/notifications/INAPP_WEB`,
+      params,
+      customAuthorization
+    );
+  };
+
+  /** Used to update a scheduled notification. */
   updateSchedule = async (
     trackingId: string,
     sendRequest: Partial<SendRequest>