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Decode and inspect JWT tokens instantly in your browser. No data is sent to any server.
Copy and paste a JWT token string into the input field.
The header and payload are decoded and formatted as JSON instantly.
The tool highlights whether the token is still valid or has expired.
A JSON Web Token (JWT) is a compact, signed token used to pass identity and claims between a client and a server. It has three parts separated by dots: a header, a payload, and a signature. The header and payload are Base64URL-encoded JSON, which means anyone can read them. The signature proves the token was issued by a trusted party and was not changed.
This decoder splits a token, Base64URL-decodes the header and payload, and shows the JSON along with useful details like the algorithm, the issued-at time, and whether the token has expired. Everything happens in your browser, so the token never leaves your device.
The header names the algorithm (such as HS256 or RS256) and the token type. The payload holds the claims, which are statements about the user and the token, including registered claims like sub (subject), iat (issued at), exp (expiry), and any custom claims your app adds. The signature is a hash of the header and payload created with a secret or private key.
Decoding only reads the header and payload, which are not encrypted, just encoded. Verifying checks the signature against the secret or public key to confirm the token is authentic and untampered. Verification needs the key and is a server-side operation, so this tool decodes and inspects but does not verify the signature.
iss is the issuer, aud is the intended audience, sub is the subject (usually a user id), exp is the Unix timestamp when the token expires, and iat is when it was issued. If exp is in the past, the token is expired and most servers will reject it. This decoder converts those timestamps into readable dates for you.
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