JWT 디코더
A JWT (JSON Web Token) is a short string a server issues to prove who a user is — used for login sessions and API authorisation. Paste one to read its header and payload, check the expiry and issued-at times, and debug auth flows. Decoding happens in your browser and does not verify the signature.
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What is a JWT?
A JSON Web Token is three Base64URL parts joined by dots: header.payload.signature. The header names the signing algorithm, the payload holds claims such as the user ID and expiry time, and the signature lets the server prove the token was not altered.
The first two parts are only encoded, not encrypted — anyone holding the token can read them, so never put passwords or secrets in a JWT. Decoding here is safe but does not prove the token is valid: only a server with the signing key can verify the signature.
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