JWT Decoder

Decode and verify JSON Web Tokens.

Paste a token to see header/payload JSON, expiration details, and signature validity. We never store or transmit your data.

Supports HS256 / HS384 / HS512
Runs Locally in your browser
Output JSON + diagnostics

JWT input

Tip: signature checks only work for HMAC-based tokens. For RSA/ECDSA, use your key material and validation tooling.

Diagnostics

Waiting for token

Header

Payload

--

Signature

--
Expected --

Timestamps

--

Issues

  • Waiting for token input.

JWT decoding tips

Signature mismatch

Use the exact secret, algorithm, and token string. Any whitespace changes the HMAC.

Expired tokens

Check exp/nbf/iat values and compare to the issuer clock for drift.

Algorithm confusion

Ensure the header alg matches your verifier selection and your auth provider settings.