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JWT Decoder

JWT Decoder decodes a JSON Web Token and displays the header and payload as formatted JSON. Useful for debugging authentication issues — all decoding happens locally in your browser; the token is never sent anywhere.

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How to decode a JWT

  1. 1 Paste a JSON Web Token (the three-part dot-separated string) into the input field.
  2. 2 The header and payload are decoded and displayed as formatted JSON.
  3. 3 Expiry time (exp claim) is shown as a human-readable date if present.

Frequently Asked Questions

Is the token sent anywhere?
No — decoding is done entirely in your browser with JavaScript's atob() function. The token never leaves your device.
Does this verify the signature?
No — this tool only decodes (Base64URL-decodes) the header and payload. Signature verification requires the secret key and is not performed.
Why is my JWT invalid?
A valid JWT has exactly two dots separating three Base64URL-encoded parts. Check that the token is complete and not truncated.

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