diff --git a/packages/auth/karma.conf.js b/packages/auth/karma.conf.js
index 6845f0bd91d..198b079a15b 100644
--- a/packages/auth/karma.conf.js
+++ b/packages/auth/karma.conf.js
@@ -65,7 +65,8 @@ function getTestFiles(argv) {
       'src/**/*.test.ts',
       'test/helpers/**/*.test.ts',
       'test/integration/flows/anonymous.test.ts',
-      'test/integration/flows/email.test.ts'
+      'test/integration/flows/email.test.ts',
+      'test/integration/flows/firebaseserverapp.test.ts'
     ];
   }
 }
diff --git a/packages/auth/scripts/run_node_tests.ts b/packages/auth/scripts/run_node_tests.ts
index 2bfc593d8fd..ce913612f64 100644
--- a/packages/auth/scripts/run_node_tests.ts
+++ b/packages/auth/scripts/run_node_tests.ts
@@ -48,7 +48,9 @@ let testConfig = [
 ];
 
 if (argv.integration) {
-  testConfig = ['test/integration/flows/{email,anonymous}.test.ts'];
+  testConfig = [
+    'test/integration/flows/{email,anonymous,firebaseserverapp}.test.ts'
+  ];
   if (argv.local) {
     testConfig.push('test/integration/flows/*.local.test.ts');
   }
diff --git a/packages/auth/test/integration/flows/firebaseserverapp.test.ts b/packages/auth/test/integration/flows/firebaseserverapp.test.ts
new file mode 100644
index 00000000000..9629320172f
--- /dev/null
+++ b/packages/auth/test/integration/flows/firebaseserverapp.test.ts
@@ -0,0 +1,344 @@
+/**
+ * @license
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { expect, use } from 'chai';
+import chaiAsPromised from 'chai-as-promised';
+
+// eslint-disable-next-line import/no-extraneous-dependencies
+import {
+  Auth,
+  OperationType,
+  createUserWithEmailAndPassword,
+  getAdditionalUserInfo,
+  getAuth,
+  onAuthStateChanged,
+  signInAnonymously,
+  signOut,
+  updateProfile
+} from '@firebase/auth';
+import { isBrowser } from '@firebase/util';
+import { initializeServerApp } from '@firebase/app';
+
+import {
+  cleanUpTestInstance,
+  getTestInstance,
+  randomEmail
+} from '../../helpers/integration/helpers';
+
+use(chaiAsPromised);
+
+const signInWaitDuration = 200;
+
+describe('Integration test: Auth FirebaseServerApp tests', () => {
+  let auth: Auth;
+  let serverAppAuth: Auth | null;
+
+  beforeEach(() => {
+    auth = getTestInstance();
+  });
+
+  afterEach(async () => {
+    if (serverAppAuth) {
+      await signOut(serverAppAuth);
+      serverAppAuth = null;
+    }
+    await cleanUpTestInstance(auth);
+  });
+
+  it('signs in with anonymous user', async () => {
+    if (isBrowser()) {
+      return;
+    }
+    const userCred = await signInAnonymously(auth);
+    expect(auth.currentUser).to.eq(userCred.user);
+    expect(userCred.operationType).to.eq(OperationType.SIGN_IN);
+    const user = userCred.user;
+    expect(user).to.equal(auth.currentUser);
+    expect(user.isAnonymous).to.be.true;
+    expect(user.uid).to.be.a('string');
+    expect(user.emailVerified).to.be.false;
+    expect(user.providerData.length).to.equal(0);
+
+    const authIdToken = await user.getIdToken();
+    const firebaseServerAppSettings = { authIdToken };
+
+    const serverApp = initializeServerApp(auth.app, firebaseServerAppSettings);
+    serverAppAuth = getAuth(serverApp);
+    let numberServerLogins = 0;
+    onAuthStateChanged(serverAppAuth, serverAuthUser => {
+      if (serverAuthUser) {
+        numberServerLogins++;
+
+        // Note, the serverAuthUser does not fully equal the standard Auth user
+        // since the serverAuthUser does not have a refresh token.
+        expect(user.uid).to.be.equal(serverAuthUser.uid);
+        expect(user.isAnonymous).to.be.equal(serverAuthUser.isAnonymous);
+        expect(user.emailVerified).to.be.equal(serverAuthUser.emailVerified);
+        expect(user.providerData.length).to.eq(
+          serverAuthUser.providerData.length
+        );
+      }
+    });
+
+    await new Promise(resolve => {
+      setTimeout(resolve, signInWaitDuration);
+    });
+
+    expect(numberServerLogins).to.equal(1);
+  });
+
+  it('getToken operations fullfilled or rejected', async () => {
+    if (isBrowser()) {
+      return;
+    }
+    const userCred = await signInAnonymously(auth);
+    expect(auth.currentUser).to.eq(userCred.user);
+    expect(userCred.operationType).to.eq(OperationType.SIGN_IN);
+    const user = userCred.user;
+    expect(user).to.equal(auth.currentUser);
+    expect(user.isAnonymous).to.be.true;
+    expect(user.uid).to.be.a('string');
+
+    const authIdToken = await user.getIdToken();
+    const firebaseServerAppSettings = { authIdToken };
+
+    const serverApp = initializeServerApp(auth.app, firebaseServerAppSettings);
+    serverAppAuth = getAuth(serverApp);
+    let numberServerLogins = 0;
+    onAuthStateChanged(serverAppAuth, serverAuthUser => {
+      if (serverAuthUser) {
+        numberServerLogins++;
+        expect(user.uid).to.be.equal(serverAuthUser.uid);
+        expect(serverAppAuth).to.not.be.null;
+        expect(serverAuthUser.getIdToken);
+        if (serverAppAuth) {
+          expect(serverAppAuth.currentUser).to.equal(serverAuthUser);
+        }
+      }
+    });
+
+    await new Promise(resolve => {
+      setTimeout(resolve, signInWaitDuration);
+    });
+
+    expect(numberServerLogins).to.equal(1);
+    expect(serverAppAuth.currentUser).to.not.be.null;
+    if (serverAppAuth.currentUser) {
+      const idToken = await serverAppAuth.currentUser.getIdToken(
+        /*forceRefresh=*/ false
+      );
+      expect(idToken).to.not.be.null;
+      await expect(serverAppAuth.currentUser.getIdToken(/*forceRefresh=*/ true))
+        .to.be.rejected;
+    }
+  });
+
+  it('signs in with email crednetial user', async () => {
+    if (isBrowser()) {
+      return;
+    }
+    const email = randomEmail();
+    const password = 'password';
+    const userCred = await createUserWithEmailAndPassword(
+      auth,
+      email,
+      password
+    );
+    const user = userCred.user;
+    expect(auth.currentUser).to.eq(userCred.user);
+    expect(userCred.operationType).to.eq(OperationType.SIGN_IN);
+
+    const additionalUserInfo = getAdditionalUserInfo(userCred)!;
+    expect(additionalUserInfo.isNewUser).to.be.true;
+    expect(additionalUserInfo.providerId).to.eq('password');
+    expect(user.isAnonymous).to.be.false;
+    expect(user.email).to.equal(email);
+
+    const authIdToken = await user.getIdToken();
+    const firebaseServerAppSettings = { authIdToken };
+
+    const serverApp = initializeServerApp(auth.app, firebaseServerAppSettings);
+    serverAppAuth = getAuth(serverApp);
+    let numberServerLogins = 0;
+    onAuthStateChanged(serverAppAuth, serverAuthUser => {
+      if (serverAuthUser) {
+        numberServerLogins++;
+        expect(serverAppAuth).to.not.be.null;
+        if (serverAppAuth) {
+          expect(serverAppAuth.currentUser).to.equal(serverAuthUser);
+        }
+        expect(user.uid).to.be.equal(serverAuthUser.uid);
+        expect(serverAuthUser.refreshToken).to.be.empty;
+        expect(user.isAnonymous).to.be.equal(serverAuthUser.isAnonymous);
+        expect(user.emailVerified).to.be.equal(serverAuthUser.emailVerified);
+        expect(user.providerData.length).to.eq(
+          serverAuthUser.providerData.length
+        );
+        expect(user.email).to.equal(serverAuthUser.email);
+      }
+    });
+
+    await new Promise(resolve => {
+      setTimeout(resolve, signInWaitDuration);
+    });
+
+    expect(numberServerLogins).to.equal(1);
+  });
+
+  it('can reload user', async () => {
+    if (isBrowser()) {
+      return;
+    }
+    const userCred = await signInAnonymously(auth);
+    expect(auth.currentUser).to.eq(userCred.user);
+
+    const user = userCred.user;
+    expect(user).to.equal(auth.currentUser);
+    expect(user.uid).to.be.a('string');
+
+    const authIdToken = await user.getIdToken();
+    const firebaseServerAppSettings = { authIdToken };
+
+    const serverApp = initializeServerApp(auth.app, firebaseServerAppSettings);
+    serverAppAuth = getAuth(serverApp);
+    let numberServerLogins = 0;
+    onAuthStateChanged(serverAppAuth, serverAuthUser => {
+      if (serverAuthUser) {
+        numberServerLogins++;
+        expect(user.uid).to.be.equal(serverAuthUser.uid);
+        expect(serverAppAuth).to.not.be.null;
+        if (serverAppAuth) {
+          expect(serverAppAuth.currentUser).to.equal(serverAuthUser);
+        }
+      }
+    });
+
+    await new Promise(resolve => {
+      setTimeout(resolve, signInWaitDuration);
+    });
+
+    expect(serverAppAuth.currentUser).to.not.be.null;
+    if (serverAppAuth.currentUser) {
+      await serverAppAuth.currentUser.reload();
+    }
+    expect(numberServerLogins).to.equal(1);
+  });
+
+  it('can update server based user profile', async () => {
+    if (isBrowser()) {
+      return;
+    }
+    const userCred = await signInAnonymously(auth);
+    expect(auth.currentUser).to.eq(userCred.user);
+
+    const user = userCred.user;
+    expect(user).to.equal(auth.currentUser);
+    expect(user.uid).to.be.a('string');
+    expect(user.displayName).to.be.null;
+
+    const authIdToken = await user.getIdToken();
+    const firebaseServerAppSettings = { authIdToken };
+
+    const serverApp = initializeServerApp(auth.app, firebaseServerAppSettings);
+    serverAppAuth = getAuth(serverApp);
+    let numberServerLogins = 0;
+    const newDisplayName = 'newName';
+    onAuthStateChanged(serverAppAuth, serverAuthUser => {
+      if (serverAuthUser) {
+        numberServerLogins++;
+        expect(serverAppAuth).to.not.be.null;
+        if (serverAppAuth) {
+          expect(serverAppAuth.currentUser).to.equal(serverAuthUser);
+        }
+        expect(user.uid).to.be.equal(serverAuthUser.uid);
+        expect(user.displayName).to.be.null;
+        void updateProfile(serverAuthUser, {
+          displayName: newDisplayName
+        });
+      }
+    });
+
+    await new Promise(resolve => {
+      setTimeout(resolve, signInWaitDuration);
+    });
+
+    expect(serverAppAuth.currentUser).to.not.be.null;
+
+    if (serverAppAuth.currentUser) {
+      await serverAppAuth.currentUser.reload();
+    }
+
+    expect(numberServerLogins).to.equal(1);
+    expect(serverAppAuth).to.not.be.null;
+    if (serverAppAuth) {
+      expect(serverAppAuth.currentUser).to.not.be.null;
+      expect(serverAppAuth.currentUser?.displayName).to.not.be.null;
+      expect(serverAppAuth.currentUser?.displayName).to.equal(newDisplayName);
+    }
+  });
+
+  it('can sign out of main auth and still use server auth', async () => {
+    if (isBrowser()) {
+      return;
+    }
+    const userCred = await signInAnonymously(auth);
+    expect(auth.currentUser).to.eq(userCred.user);
+
+    const user = userCred.user;
+    expect(user).to.equal(auth.currentUser);
+    expect(user.uid).to.be.a('string');
+    expect(user.displayName).to.be.null;
+
+    const authIdToken = await user.getIdToken();
+    const firebaseServerAppSettings = { authIdToken };
+
+    const serverApp = initializeServerApp(
+      auth.app.options,
+      firebaseServerAppSettings
+    );
+    serverAppAuth = getAuth(serverApp);
+    let numberServerLogins = 0;
+    onAuthStateChanged(serverAppAuth, serverAuthUser => {
+      if (serverAuthUser) {
+        numberServerLogins++;
+        expect(serverAppAuth).to.not.be.null;
+        expect(user.uid).to.be.equal(serverAuthUser.uid);
+        expect(user.displayName).to.be.null;
+        if (serverAppAuth) {
+          expect(serverAppAuth.currentUser).to.equal(serverAuthUser);
+        }
+      }
+    });
+
+    await signOut(auth);
+    await new Promise(resolve => {
+      setTimeout(resolve, signInWaitDuration);
+    });
+
+    expect(serverAppAuth.currentUser).to.not.be.null;
+
+    if (serverAppAuth.currentUser) {
+      await serverAppAuth.currentUser.reload();
+    }
+
+    expect(numberServerLogins).to.equal(1);
+    expect(serverAppAuth).to.not.be.null;
+    if (serverAppAuth) {
+      expect(serverAppAuth.currentUser).to.not.be.null;
+    }
+  });
+});