diff --git a/backend/src/apis/humhub/ExportUsers.ts b/backend/src/apis/humhub/ExportUsers.ts
index de33ba779..8a40d480d 100644
--- a/backend/src/apis/humhub/ExportUsers.ts
+++ b/backend/src/apis/humhub/ExportUsers.ts
@@ -24,7 +24,7 @@ function getUsersPage(page: number, limit: number): Promise<[User[], number]> {
 
 /**
  * @param client
- * @returns user map indiced with email
+ * @returns user map indices with email
  */
 async function loadUsersFromHumHub(client: HumHubClient): Promise<Map<string, GetUser>> {
   const start = new Date().getTime()
diff --git a/backend/src/apis/humhub/__mocks__/HumHubClient.ts b/backend/src/apis/humhub/__mocks__/HumHubClient.ts
new file mode 100644
index 000000000..a11d8f407
--- /dev/null
+++ b/backend/src/apis/humhub/__mocks__/HumHubClient.ts
@@ -0,0 +1,50 @@
+import { User } from '@entity/User'
+import { UserContact } from '@entity/UserContact'
+
+import { GetUser } from '@/apis/humhub/model/GetUser'
+import { PostUser } from '@/apis/humhub/model/PostUser'
+import { UsersResponse } from '@/apis/humhub/model/UsersResponse'
+
+/**
+ * HumHubClient as singleton class
+ */
+export class HumHubClient {
+  // eslint-disable-next-line no-use-before-define
+  private static instance: HumHubClient
+
+  // eslint-disable-next-line no-useless-constructor, @typescript-eslint/no-empty-function
+  private constructor() {}
+
+  public static getInstance(): HumHubClient {
+    if (!HumHubClient.instance) {
+      HumHubClient.instance = new HumHubClient()
+    }
+    return HumHubClient.instance
+  }
+
+  public async users(): Promise<UsersResponse | null> {
+    return Promise.resolve(new UsersResponse())
+  }
+
+  public async userByEmail(email: string): Promise<GetUser | null> {
+    const user = new User()
+    user.emailContact = new UserContact()
+    user.emailContact.email = email
+    return Promise.resolve(new GetUser(user, 1))
+  }
+
+  public async createUser(): Promise<void> {
+    return Promise.resolve()
+  }
+
+  public async updateUser(inputUser: PostUser, humhubUserId: number): Promise<GetUser | null> {
+    const user = new User()
+    user.emailContact = new UserContact()
+    user.emailContact.email = inputUser.account.email
+    return Promise.resolve(new GetUser(user, humhubUserId))
+  }
+
+  public async deleteUser(): Promise<void> {
+    return Promise.resolve()
+  }
+}
diff --git a/backend/src/apis/humhub/__mocks__/syncUser.ts b/backend/src/apis/humhub/__mocks__/syncUser.ts
new file mode 100644
index 000000000..7e0660da4
--- /dev/null
+++ b/backend/src/apis/humhub/__mocks__/syncUser.ts
@@ -0,0 +1,44 @@
+import { User } from '@entity/User'
+
+import { isHumhubUserIdenticalToDbUser } from '@/apis/humhub/compareHumhubUserDbUser'
+import { GetUser } from '@/apis/humhub/model/GetUser'
+
+export enum ExecutedHumhubAction {
+  UPDATE,
+  CREATE,
+  SKIP,
+  DELETE,
+}
+/**
+ * Trigger action according to conditions
+ * | User exist on humhub | export to humhub allowed | changes in user data | ACTION
+ * |      true            |         false            |       ignored        | DELETE
+ * |      true            |         true             |        true          | UPDATE
+ * |      true            |         true             |        false         | SKIP
+ * |      false           |         false            |       ignored        | SKIP
+ * |      false           |         true             |       ignored        | CREATE
+ * @param user
+ * @param humHubClient
+ * @param humhubUsers
+ * @returns
+ */
+export async function syncUser(
+  user: User,
+  humhubUsers: Map<string, GetUser>,
+): Promise<ExecutedHumhubAction> {
+  const humhubUser = humhubUsers.get(user.emailContact.email.trim())
+  if (humhubUser) {
+    if (!user.humhubAllowed) {
+      return Promise.resolve(ExecutedHumhubAction.DELETE)
+    }
+    if (!isHumhubUserIdenticalToDbUser(humhubUser, user)) {
+      // if humhub allowed
+      return Promise.resolve(ExecutedHumhubAction.UPDATE)
+    }
+  } else {
+    if (user.humhubAllowed) {
+      return Promise.resolve(ExecutedHumhubAction.CREATE)
+    }
+  }
+  return Promise.resolve(ExecutedHumhubAction.SKIP)
+}
diff --git a/backend/src/apis/humhub/syncUser.test.ts b/backend/src/apis/humhub/syncUser.test.ts
index d99d15156..20a6b2c33 100644
--- a/backend/src/apis/humhub/syncUser.test.ts
+++ b/backend/src/apis/humhub/syncUser.test.ts
@@ -2,47 +2,16 @@
 import { User } from '@entity/User'
 import { UserContact } from '@entity/UserContact'
 
-import { CONFIG } from '@/config'
-
-import { HumHubClient } from './HumHubClient'
 import { GetUser } from './model/GetUser'
 import { syncUser, ExecutedHumhubAction } from './syncUser'
 
+jest.mock('@/apis/humhub/HumHubClient')
+
 const defaultUser = new User()
 defaultUser.emailContact = new UserContact()
 defaultUser.emailContact.email = 'email@gmail.com'
 
-CONFIG.HUMHUB_ACTIVE = true
-CONFIG.HUMHUB_API_URL = 'http://localhost'
-
-let humhubClient: HumHubClient | undefined
-let humhubClientSpy: {
-  createUser: jest.SpyInstance
-  updateUser: jest.SpyInstance
-  deleteUser: jest.SpyInstance
-}
-
 describe('syncUser function', () => {
-  beforeAll(() => {
-    humhubClient = HumHubClient.getInstance()
-    if (!humhubClient) {
-      throw new Error('error creating humhub client')
-    }
-    humhubClientSpy = {
-      createUser: jest.spyOn(humhubClient, 'createUser'),
-      updateUser: jest.spyOn(humhubClient, 'updateUser'),
-      deleteUser: jest.spyOn(humhubClient, 'deleteUser'),
-    }
-    humhubClientSpy.createUser.mockImplementation(() => Promise.resolve())
-    humhubClientSpy.updateUser.mockImplementation(() => Promise.resolve())
-    humhubClientSpy.deleteUser.mockImplementation(() => Promise.resolve())
-  })
-
-  afterEach(() => {
-    humhubClientSpy.createUser.mockClear()
-    humhubClientSpy.updateUser.mockClear()
-    humhubClientSpy.deleteUser.mockClear()
-  })
   afterAll(() => {
     jest.resetAllMocks()
   })
diff --git a/backend/src/graphql/resolver/UserResolver.ts b/backend/src/graphql/resolver/UserResolver.ts
index 436c0aa83..33a351730 100644
--- a/backend/src/graphql/resolver/UserResolver.ts
+++ b/backend/src/graphql/resolver/UserResolver.ts
@@ -79,6 +79,7 @@ import { getKlicktippState } from './util/getKlicktippState'
 import { Location2Point } from './util/Location2Point'
 import { setUserRole, deleteUserRole } from './util/modifyUserRole'
 import { sendUserToGms } from './util/sendUserToGms'
+import { syncHumhub } from './util/syncHumhub'
 import { validateAlias } from './util/validateAlias'
 
 const LANGUAGES = ['de', 'en', 'es', 'fr', 'nl']
@@ -670,6 +671,9 @@ export class UserResolver {
         logger.debug(`gms-user update successfully.`)
       }
     }
+    if (CONFIG.HUMHUB_ACTIVE) {
+      await syncHumhub(updateUserInfosArgs, user)
+    }
 
     return true
   }
diff --git a/backend/src/graphql/resolver/util/syncHumhub.test.ts b/backend/src/graphql/resolver/util/syncHumhub.test.ts
new file mode 100644
index 000000000..c7b187f23
--- /dev/null
+++ b/backend/src/graphql/resolver/util/syncHumhub.test.ts
@@ -0,0 +1,63 @@
+import { User } from '@entity/User'
+import { UserContact } from '@entity/UserContact'
+
+import { HumHubClient } from '@/apis/humhub/HumHubClient'
+import { GetUser } from '@/apis/humhub/model/GetUser'
+import { ExecutedHumhubAction } from '@/apis/humhub/syncUser'
+import { UpdateUserInfosArgs } from '@/graphql/arg/UpdateUserInfosArgs'
+import { PublishNameType } from '@/graphql/enum/PublishNameType'
+import { backendLogger as logger } from '@/server/logger'
+
+import { syncHumhub } from './syncHumhub'
+
+jest.mock('@/apis/humhub/HumHubClient')
+jest.mock('@/apis/humhub/syncUser')
+
+const mockUser = new User()
+mockUser.humhubAllowed = true
+mockUser.emailContact = new UserContact()
+mockUser.emailContact.email = 'email@gmail.com'
+mockUser.humhubPublishName = PublishNameType.PUBLISH_NAME_FULL
+const mockUpdateUserInfosArg = new UpdateUserInfosArgs()
+const mockHumHubUser = new GetUser(mockUser, 1)
+
+describe('syncHumhub', () => {
+  beforeAll(() => {
+    // humhubClientMockbBeforeAll()
+  })
+
+  beforeEach(() => {
+    jest.spyOn(logger, 'debug').mockImplementation()
+    jest.spyOn(logger, 'info').mockImplementation()
+    jest.spyOn(HumHubClient, 'getInstance')
+  })
+
+  afterEach(() => {
+    // humhubClientMockbAfterEach()
+  })
+  afterAll(() => {
+    jest.resetAllMocks()
+  })
+
+  it('Should not sync if no relevant changes', async () => {
+    await syncHumhub(mockUpdateUserInfosArg, new User())
+    expect(HumHubClient.getInstance).not.toBeCalled()
+    // language logging from some other place
+    expect(logger.debug).toBeCalledTimes(4)
+    expect(logger.info).toBeCalledTimes(0)
+  })
+
+  it('Should retrieve user from humhub and sync if relevant changes', async () => {
+    mockUpdateUserInfosArg.firstName = 'New' // Relevant changes
+    mockUser.firstName = 'New'
+    await syncHumhub(mockUpdateUserInfosArg, mockUser)
+    expect(logger.debug).toHaveBeenCalledTimes(7) // Four language logging calls, two debug calls in function, one for not syncing
+    expect(logger.info).toHaveBeenLastCalledWith('finished sync user with humhub', {
+      localId: mockUser.id,
+      externId: mockHumHubUser.id,
+      result: ExecutedHumhubAction.UPDATE,
+    })
+  })
+
+  // Add more test cases as needed...
+})
diff --git a/backend/src/graphql/resolver/util/syncHumhub.ts b/backend/src/graphql/resolver/util/syncHumhub.ts
new file mode 100644
index 000000000..1ed1af7ab
--- /dev/null
+++ b/backend/src/graphql/resolver/util/syncHumhub.ts
@@ -0,0 +1,42 @@
+import { User } from '@entity/User'
+
+import { HumHubClient } from '@/apis/humhub/HumHubClient'
+import { GetUser } from '@/apis/humhub/model/GetUser'
+import { syncUser } from '@/apis/humhub/syncUser'
+import { UpdateUserInfosArgs } from '@/graphql/arg/UpdateUserInfosArgs'
+import { backendLogger as logger } from '@/server/logger'
+
+export async function syncHumhub(
+  updateUserInfosArg: UpdateUserInfosArgs,
+  user: User,
+): Promise<void> {
+  // check for humhub relevant changes
+  if (
+    !updateUserInfosArg.alias &&
+    !updateUserInfosArg.firstName &&
+    !updateUserInfosArg.lastName &&
+    !updateUserInfosArg.humhubAllowed &&
+    !updateUserInfosArg.humhubPublishName &&
+    !updateUserInfosArg.language
+  ) {
+    return
+  }
+  logger.debug('changed user-settings relevant for humhub-user update...')
+  const humhubClient = HumHubClient.getInstance()
+  if (!humhubClient) {
+    return
+  }
+  logger.debug('retrieve user from humhub')
+  const humhubUser = await humhubClient.userByEmail(user.emailContact.email)
+  const humhubUsers = new Map<string, GetUser>()
+  if (humhubUser) {
+    humhubUsers.set(user.emailContact.email, humhubUser)
+  }
+  logger.debug('update user at humhub')
+  const result = await syncUser(user, humhubUsers)
+  logger.info('finished sync user with humhub', {
+    localId: user.id,
+    externId: humhubUser?.id,
+    result,
+  })
+}