By Quick answer: How do I add Google login to my app?
- Google Cloud — create a project, consent screen and OAuth client IDs per platform.
- Android — Credential Manager is the current recommended API.
- iOS — Google Sign-In SDK; add Sign in with Apple to meet App Store rules.
- Web — Google Identity Services (the button and One Tap).
- Server — verify the ID token, then create your own session.
Key takeaways
- One-tap sign-in removes passwords, a common reason users abandon sign-up.
- An ID token is only trustworthy after your server verifies its signature, audience and expiry.
- Link accounts by verified email carefully to avoid duplicate or hijacked accounts.
- Firebase Authentication or a similar service handles most of this for small teams.
- Ask for the minimum scopes — basic profile and email are enough for login.
Every extra field on a sign-up form is a small exit door. Passwords are the biggest one: people forget them, reuse them and abandon forms to avoid creating them. "Continue with Google" replaces all of that with one tap. Done properly, it is also more secure than a homemade password system. Done carelessly, it is a way to log in as someone else.
How it works in one picture
- The user taps Continue with Google in your app.
- Google shows its account picker and consent; the user chooses an account.
- Your app receives an ID token — a signed statement from Google about who the user is.
- Your app sends the ID token to your server.
- Your server verifies the token and finds or creates the user.
- Your server issues its own session to the app.
The critical step is 5. An ID token is only trustworthy after your server has checked it4.
Step 1: set up Google Cloud
- Create a project in the Google Cloud console
- Configure the OAuth consent screen: app name, logo, support email, privacy policy and authorised domain
- Request only the openid, email and profile scopes for login
- Create OAuth client IDs for each platform: Android (with your package name and SHA-1 signing fingerprint), iOS (bundle ID), and Web (also used by your server to verify tokens)
Step 2: add it to each platform
| Platform | Recommended approach | Notes |
|---|---|---|
| Android | Credential Manager with the Google ID option1 | Replaces the older Google Sign-In for Android library |
| iOS | Google Sign-In SDK for iOS3 | Pair with Sign in with Apple for App Store rules |
| Web | Google Identity Services — the Sign in with Google button and One Tap2 | Replaces the older Google Sign-In JavaScript library |
| Flutter / React Native | Official or well-maintained plugins wrapping the above | Or Firebase Authentication |
Step 3: verify the token on your server
Using Google's server library, check that the token's signature is valid, the audience matches your client ID, the issuer is Google, and it has not expired4. Then use the token's stable user ID (sub) as the link to your user record — not the email, which can change.
Step 4: handle account linking
Same email, existing password account
Ask the user to sign in with their password once to link Google, rather than silently merging.
Google first, password later
Let them add a password from settings if they want one.
Unverified email
Only trust an email for linking if the token marks it as verified.
Step 5: meet Apple's rule
If your iOS app uses a third-party login such as Google for the main account, Apple's guideline 4.8 generally requires you to also offer an equivalent option with privacy protections — Sign in with Apple meets it5. Plan for both buttons from the start.
Design the sign-in screen well
- Use Google's official button styles and wording ("Sign in with Google" / "Continue with Google")
- Show social options above email, with equal visual weight for Google and Apple on iOS
- Explain why an account is needed — or let people explore before signing in
- Handle cancel and error states gracefully
Sign-up is often where onboarding leaks most. An onboarding audit finds where people drop off.
Key terms, defined
OAuth 2.0 — the standard for delegated authorisation. OpenID Connect — the identity layer on top of OAuth used for sign-in. ID token — a signed token describing the signed-in user. Client ID — your app's identifier with Google. Scope — the data or access requested. Credential Manager — Android's unified sign-in API.
Frequently asked questions
Is Login with Google free?
Yes. Google does not charge for Sign in with Google. If you use a managed auth service such as Firebase Authentication, check its pricing for your expected number of monthly active users.
What is Credential Manager on Android?
Credential Manager is Android's Jetpack API that brings passwords, passkeys and federated sign-in such as Sign in with Google into one interface. Google recommends it for new Sign in with Google integrations on Android.
Do I need Sign in with Apple if I add Google login?
On the App Store, apps that use a third-party or social login for the primary account generally must also offer an equivalent login option with privacy protections, and Sign in with Apple meets that requirement. There are exceptions, such as apps using only your company's own account system.
How do I verify a Google ID token?
On your server, use Google's client library to verify the token's signature, check that the audience matches your client ID, the issuer is Google, and it has not expired. Then use the stable user ID ('sub') to find or create the user.
Should I use Firebase for Google login?
For many small and medium apps, yes. Firebase Authentication wraps Google, Apple, phone and email sign-in, handles tokens and sessions, and works across Android, iOS, web and Flutter. Larger teams may prefer their own auth service or another identity provider.
Why does Google show an 'unverified app' warning?
Apps requesting sensitive or restricted scopes need Google's verification. For basic login, request only the openid, email and profile scopes, complete your consent screen with a privacy policy and domain, and publish it.
Sources
- Android Developers — Authenticate users with Sign in with Google (Credential Manager)
- Google for Developers — Sign in with Google for Web (Google Identity Services)
- Google for Developers — Google Sign-In for iOS
- Google for Developers — Verify the Google ID token on your server side
- Apple Developer — App Store Review Guidelines (4.8 Login Services)
- Checked October 23, 2026. Figures that change — fees, salaries, prices — are reviewed every six months; if something is out of date, tell us.
Where to go from here
- How to add payments to your app — the same 'trust the server' principle
- Onboarding audit — find where sign-up loses people
- How to make an appHow to add payments to your app: Razorpay vs Stripe setup for Indian appsAdd payments to your app safely: choose Razorpay or Stripe, create orders on your server, verify signatures and webhooks, and follow app-store rules.
- How to make an appHow to convert a website into an app in a dayTurn your website into an app in a day: make it a PWA, ship it to Google Play as a Trusted Web Activity, or wrap it with Capacitor without an Apple rejection.
- App developmentGoogle Play developer account: cost, setup and verificationA Google Play developer account costs a one-time US$25. Personal vs organisation, documents, D-U-N-S, identity checks and the 12-tester rule.
- How to make an appHow to make an iPhone app without a MacFive real ways to build an iPhone app without a Mac: cross-platform code with cloud builds, Expo EAS, Codemagic, a rented cloud Mac, or Swift Playground.
- How to make an appHow to make an Android app from scratchMake your first Android app with Android Studio, Kotlin and Jetpack Compose: setup, first screen, state, data, testing on a phone and publishing on Google Play.
- Making moneyApp developer salary in India: Android, iOS, Flutter and React Native pay in 2027App developer salary in India by platform and experience — Android, iOS, Flutter, React Native — from AmbitionBox data (Oct 2026), plus what moves pay up.
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