JWT Decoder

Decode a JWT's header and payload.

What it does

Paste a JSON Web Token and this tool splits it into its three parts, base64url-decodes the header and payload, and displays them as readable JSON — including common claims like exp, iat, and sub.

Common errors

Decoding doesn't verify the signature
Decoding only reveals the header and payload contents. It does not prove the token is authentic — use the JWT Generator's verify mode with the correct secret for that.

FAQ

No — decoding happens entirely in your browser using base64url decoding and JSON.parse. Nothing is sent to a server.

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