What is JWT Decoder?

Decode JWT tokens instantly. Inspect header, payload, and signature claims without sending data to any server.

FAQ

What is a JWT?

JSON Web Token (JWT) is a compact token format for authentication. It contains header (algorithm), payload (claims), and signature.

What security claims should I check?

Look for: alg (none = bypass), exp (missing = permanent access), admin (privilege escalation), kid (injection risk).

Related Tools

• JWT Attacker
• JWT Playground
• Cookie Analyzer