Developer
JWT Decoder
Inspect a JWT's header and payload locally. Signature verification is intentionally not performed.
Common questions
What is a JWT?
A JSON Web Token (JWT) is a compact, URL-safe token format used for authentication and data exchange. It consists of three Base64URL-encoded parts separated by dots: header, payload and signature. This tool decodes the header and payload for inspection.
Does this tool verify JWT signatures?
No, intentionally. Signature verification requires the signing key, which this tool does not have. The purpose is to inspect the contents of a token you have received, not to authenticate it. Use your application's JWT library for verification.
What information is in the header and payload?
The header typically contains the algorithm (alg) and token type (typ). The payload contains claims: issuer (iss), subject (sub), expiration (exp), issued-at (iat), and any custom claims. The tool formats both as readable JSON.