developer-tools
JWT Decoder
Decode a JWT header and payload locally in your browser, including alg, typ, sub, iss, aud, iat, exp, and nbf claims.
Tool workspace
The interactive tool requires JavaScript.
Instructions
2. Click ?Decode JWT? to inspect the Header, Payload, signature segment, and common time claims.
3. Treat the output as a debugging clue; real authentication and authorization still require server-side verification.
Paste a test JWT to inspect the Header and Payload as readable JSON. Processing stays in your browser, and the tool does not verify signatures. Do not paste production tokens, real secrets, or private data.
JWT decoding only turns the Base64URL Header and Payload into readable JSON. It does not prove the token is authentic, unchanged, unexpired, or authorized. Important systems must verify the signature and validate claims on the server with trusted keys.
What this decoder is for
Use it to inspect JWT Header, Payload, and common claims such as alg, typ, sub, iss, aud, iat, exp, and nbf. It does not call a backend, use external APIs, or decide whether the token is trustworthy.
Decode is not verification
JWT Header and Payload are usually Base64URL encoded, so anyone can decode them. A system should only trust a token after checking the signature with the right key and validating expiration, issuer, audience, and permissions.
Sensitive-token boundary
Browser-local processing is helpful, but you should still avoid pasting production tokens, admin sessions, customer data, private keys, or secret environment values. Prefer test tokens, redacted examples, or short-lived credentials with no real permissions.