Free Developer Utility
Paste a JSON Web Token to inspect its header, payload, and signature. Registered claims (sub, iss, aud, exp, iat, nbf) are labeled, and expiry / not-before status is checked — all in your browser, no upload.
Decoding is signature-only inspection — this tool does not verify the signature (that requires the secret/public key). Everything runs in your browser; no token is uploaded.