JWT Decoder

JSON Web Tokens are compact, signed tokens that carry identity and authorization data between services. When you are debugging an auth flow, you often need to inspect the header and payload claims without verifying the signature. This JWT decoder does exactly that: it splits the token into its three parts, decodes the Base64URL segments, and renders the header and payload as readable JSON. You can quickly confirm issuer, subject, audience, scopes, and any custom claims added by your auth provider.

The decoder also highlights temporal claims like exp, iat, and nbf by converting them into human-readable timestamps. That makes it easy to spot expired tokens or time drift between services. Because the tool is entirely client-side, tokens are decoded locally and never leave your browser. This is important for security when you are examining production or staging tokens. Use this decoder to validate assumptions in your auth middleware, to confirm claim mapping, or to sanity-check that the right token is being attached to requests. It is a fast, no-friction way to peek inside a JWT while keeping your workflow safe and private.

For troubleshooting, it is helpful to compare claims across environments and confirm that scopes and audiences match what your services expect. You can also verify that time based claims align with server clocks before investigating deeper infrastructure issues. Remember that decoding is not the same as verification, so always validate signatures and issuer rules in your application.