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JWT Decoder

Paste a JSON Web Token to read its header and payload in plain JSON.

  1. Paste the token
  2. Read the decoded header and payload

Decodes only — it does not verify the signature. Nothing is sent to a server.

Decoded entirely in your browser — the token never leaves your device (there is no signature verification here, only decoding).

Frequently asked questions

Does this verify the JWT signature?
No — it only decodes the header and payload, which are just Base64URL-encoded JSON. It does not check the signature, so a decoded token isn't proof the token is valid or untampered.
Why can I read the payload without a secret key?
JWT payloads are encoded, not encrypted — anyone with the token can decode the header and payload. Only the signature (which this tool doesn't check) requires the secret or private key.
What does the decoded output show?
The header (algorithm and token type) and the payload (claims like sub, exp, iat, and any custom fields), formatted as readable JSON.
Is my token sent to a server?
No. Decoding happens entirely in your browser — the token you paste never leaves your device.
Do I need to install anything or sign up?
No. It runs entirely in your browser — no software install, no account, no email required.
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