How do I add Google login to my app?

To add Google login, you typically use Google Identity Services (GIS) and an OAuth 2.0 / OpenID Connect flow.

High-level steps

1. Create a Google Cloud project

   • Go to the Google Cloud Console.
   • Create a project or select an existing one.

2. Configure the OAuth consent screen

   • In the Cloud Console, set up the consent screen.
   • Add your app name, support email, and authorized domains.
   • If needed, add test users while in development.

3. Create OAuth client credentials

   • Create credentials for your app type:
     • Web app: set authorized JavaScript origins and redirect URIs.
     • iOS/Android: use the platform-specific client setup.
   • Save the Client ID (and Client Secret for server-side web apps).

4. Integrate Google sign-in

   • Use Google’s Sign-In / Identity Services SDK in your frontend.
   • The user clicks “Sign in with Google.”
   • Google returns an ID token and/or authorization code depending on the flow.

5. Verify the token on your backend

   • Send the ID token or auth code to your server.
   • Verify it with Google libraries.
   • Create or log in the local user in your app.
   • Establish your own session/JWT for your app.

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Recommended approach for most apps

Web app with backend

Use Google Identity Services on the frontend and verify the token on the backend.

Frontend example

<script src="https://accounts.google.com/gsi/client" async defer></script>
<div id="g_id_onload"
     data-client_id="YOUR_GOOGLE_CLIENT_ID"
     data-callback="handleCredentialResponse">
</div>
<div class="g_id_signin"></div>

<script>
  function handleCredentialResponse(response) {
    // response.credential is the ID token
    fetch('/auth/google', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ idToken: response.credential })
    });
  }
</script>

Backend verification example (Node.js)

const { OAuth2Client } = require('google-auth-library');
const client = new OAuth2Client(process.env.GOOGLE_CLIENT_ID);

app.post('/auth/google', async (req, res) => {
  const ticket = await client.verifyIdToken({
    idToken: req.body.idToken,
    audience: process.env.GOOGLE_CLIENT_ID,
  });

  const payload = ticket.getPayload();
  const googleUserId = payload.sub;
  const email = payload.email;

  // Find or create user in your database
  // Create your app session / JWT

  res.json({ success: true });
});

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Important security notes

• Always verify tokens on the backend; don’t trust the client alone.
• Use HTTPS in production.
• Restrict OAuth client settings to your exact domains/redirect URIs.
• Store secrets securely in environment variables.

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If you use a framework

I can give you a ready-to-use guide for:

• React
• Next.js
• Node/Express
• Django
• Firebase
• iOS / Android
• Flutter
• React Native

If you tell me your stack, I can provide exact code and setup steps.