Prompt
Do I need OAuth if I just want sign in with Google?
Latest observation
Oct 6, 2026
OpenAI APIWeb search: off
Yes — “Sign in with Google” uses OAuth 2.0, usually along with OpenID Connect (OIDC).
A quick way to think about it:
- OAuth 2.0 = lets your app get permission to access Google data on the user’s behalf.
- OpenID Connect = adds authentication (“who is the user?”) on top of OAuth 2.0.
- Sign in with Google = typically implemented using Google’s OAuth 2.0 / OpenID Connect flow.
So if your goal is just:
- “Let users click a button and sign in with their Google account”
then yes, you still need to use the OAuth/OIDC flow, but you usually don’t need to manually handle the full complexity yourself if you use Google’s client libraries or a third-party auth provider.
In practice
You’ll usually:
- Register your app in Google Cloud Console
- Create OAuth credentials
- Use Google’s sign-in flow
- Receive an ID token or authorization response
- Verify the token on your backend and create your own app session
Important distinction
If you only want Google login and not access to Google APIs:
- You still use OAuth/OIDC
- But you may only request the openid, email, and profile scopes
If you want, I can show you the simplest architecture for “Sign in with Google” for a web app, mobile app, or backend API.