OAuth Token Inspector — Free Online OAuth Access Token Decoder
Inspect and decode OAuth 2.0 access tokens — JWT claims, scopes, expiry, issuer, and audience — 100% client-side.
Frequently Asked Questions
Understanding OAuth 2.0 Access Tokens
OAuth 2.0 access tokens are credentials that grant access to protected resources. When a client application requests access to an API, the authorization server issues an access token with specific scopes (permissions) and a limited lifetime. The API validates this token on every request.
Modern APIs typically issue JWT (JSON Web Token) access tokens that contain claims such as the subject (user ID), issuer (auth server), audience (target API), expiration time, and granted scopes. The API can verify these claims without a database lookup by validating the token signature against the auth server's public key.
When debugging OAuth flows, the most common issues are: expired tokens (check exp claim), wrong audience (aud must match your API), missing scopes (check scope/scp claim), and incorrect issuer (iss must match your auth server URL). This tool surfaces all these claims for quick inspection.