Identity & Authentication

Google Sign-In Widget

Authenticate with Google Identity Services to inspect the returned OpenID Connect ID token (JWT) and user profile claims directly in your browser.

Documentation

About Google Sign-In & ID Tokens

  1. Google Identity Services (GIS): This page uses Google's official Sign-In SDK (https://accounts.google.com/gsi/client) to initiate client-side OAuth 2.0 / OpenID Connect authentication.
  2. ID Token (JWT): When authentication succeeds, Google returns a cryptographically signed JSON Web Token (JWT) called an ID token.
  3. Token Anatomy: The token consists of three Base64URL-encoded segments separated by periods: the Header (signing algorithm & key ID), the Payload (user identity claims), and the Signature.
  4. Identity Claims: The decoded payload contains standard OIDC claims including sub (unique Google account ID), email, given_name, family_name, picture, iat (issued at), and exp (expiration).
  5. Privacy & Security: Token inspection and Base64URL decoding occur strictly client-side within your browser. Credentials and profile data are never logged or transmitted to an external server.
  6. Written by DinoChiesa. Contact via GitHub or Bluesky.