SuperB PowerTools

JWT Decoder

Decode a JSON Web Token and inspect its header and payload.

Encoded Token
Decoded Header
Paste a JWT to see its decoded decoded header.
Decoded Payload
Paste a JWT to see its decoded decoded payload.
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How to use

  1. 1Paste a JWT into the input.
  2. 2Its decoded header and payload appear automatically.
  3. 3Optionally tick "Verify Signature" and enter the secret to check an HS256/HS384/HS512 signature.

Frequently asked questions

Does this verify the token signature?

It can, for HMAC-signed tokens (HS256/HS384/HS512) — tick "Verify Signature" and enter the secret. RSA/ECDSA-signed tokens (RS256, ES256, etc.) verify against a public key, which isn't supported yet.

Is my secret sent anywhere?

No. Verification runs entirely in your browser using the Web Crypto API — the secret is never sent, stored, or logged.

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