Free Online JWT Decoder
JSON Web Tokens authenticate a huge share of today's APIs — and debugging them means answering quick questions fast: which algorithm signed this token? When does it expire? What claims does it actually carry? This decoder unwraps the Base64URL segments and pretty-prints the header and payload the moment you paste a token, so those questions stop requiring console gymnastics.
Paste any header.payload.signature string and you get all three parts laid out: the signing algorithm, every payload claim in readable JSON with one-click copy, and the signature segment itself. NumericDate claims like iat (issued at) and exp (expires at) are translated into unambiguous UTC timestamps alongside a live Expired / Not expired status based on your device clock — invaluable when diagnosing "token expired" errors or validating refresh windows.
Privacy is structural here: decoding is plain JavaScript executed entirely on your device. The token is never transmitted, logged or stored, and because signature verification would require your secret keys, this tool deliberately never asks for them. It is an inspection window, not a validator — exactly what you want when examining tokens from staging environments, CI logs or third-party integrations.
How to Use This Tool
- Paste the token — drop the complete three-segment string into the input box.
- Read the results — header and payload render as formatted JSON; expiry status updates automatically.
- Copy what you need — each panel has its own copy button for claims, header or signature.
Benefits
- Instant full decode — header, payload and signature parsed as you type.
- Human-readable dates —
exp/iatshown as UTC timestamps with live expiry status. - Local by design — nothing leaves your browser; no secret keys ever requested.
- Clear errors — malformed segments produce specific, actionable messages.
- Free forever — unlimited decodes without signup.