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JWT Decoder

Paste a token, read what's inside — header, payload and whether it has expired.

🔒 Decoded in your browser — tokens never leave your machine · signature is not verified (that needs the secret key)

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Reading a JWT safely

A JSON Web Token is three Base64URL parts joined by dots: header.payload.signature. The header names the signing algorithm, the payload carries the claims (user ID, roles, expiry), and the signature proves the token wasn't tampered with. Decoding needs no secret — that's why you should never put sensitive data in a JWT payload; anyone holding the token can read it. This tool also reads standard time claims: it flags whether the token's exp has passed and shows issued-at and expiry as human dates.

FAQ

Is it safe to paste a real production token here?
Decoding happens entirely in your browser and nothing is transmitted — but treat live production tokens like passwords anyway. Prefer expired or development tokens when debugging in shared environments.
Why doesn't it verify the signature?
Verification requires the signing secret or public key — which should never be pasted into any website. This tool decodes and inspects; verification belongs on your server.
What does "expired" mean here?
The payload's exp claim (a Unix timestamp) is compared with your device's current time — if it's in the past, the token is flagged expired.

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