JSONTech

JWT Decoder

Decode and inspect JSON Web Tokens — view header, payload, and expiration status

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Frequently Asked Questions

Paste the full JWT token (the long string with two dots separating three parts) into the input field. The tool instantly decodes the header (algorithm, type) and payload (claims, expiration, issuer) without needing any secret key.

Yes. The decoding happens entirely in your browser using JavaScript — no data is sent to any server. JWTs are encoded (Base64URL), not encrypted, so decoding doesn't require your secret key.

A JWT has three Base64URL-encoded parts separated by dots: the Header (algorithm and token type), the Payload (claims like user ID, expiration, roles), and the Signature (cryptographic proof the token hasn't been tampered with).

Paste your token and look at the exp (expiration) claim in the decoded payload. The tool shows both the raw Unix timestamp and a human-readable date, plus an indicator showing whether the token is currently expired.