JWT Decoder — OAuth2 & Spring
Free online JWT decoder for OAuth2, OpenID Connect, and Spring Security resource-server development. Base64URL-decode header and payload JSON, read exp/iat/sub claims, and optionally verify HS256/384/512 signatures with a shared secret — all client-side. Safe for debugging staging tokens on your local machine.
- Decode access tokens from Keycloak, Auth0, Cognito, or custom issuers
- Read roles, scopes, tenant IDs, and session expiry before wiring Spring Security
- Verify HMAC signatures locally when debugging service-to-service JWTs
- Learn the difference between decode (readable) and verify (trusted) in the Quiz tab