JWT decoder online for debugging API authentication.

Paste a JWT below to decode the header and payload directly in your browser. This tool is useful for developers checking expiration, issuer, audience, or custom claims while troubleshooting API auth.

JWT token

Paste a JWT to decode the header and payload.

Why teams use a JWT decoder

A JWT decoder online helps you inspect what a token actually contains before you blame the API gateway, identity provider, or backend service. Many auth issues are simple claim mismatches such as the wrong audience, an expired token, or a missing issuer.

Check exp and iat values during auth debugging.
Confirm iss and aud claims match your API validation rules.
Spot dangerous token patterns like alg: none in test environments.

Decoded header

{}

Decoded payload

{}

Security note

This decoder does not verify the signature. Use it to inspect token structure, then validate signatures and issuer configuration in your API or auth middleware.

Next tool

After decoding a token, use the API header checker to review transport and caching controls on the endpoint that accepts it.