Security
JWT Decoder
Decode, verify, and debug JSON Web Tokens without sending them to a server.
Header
Decoded header will appear here.
Payload
Decoded payload will appear here.
About JWT Debugger
This JWT Decoder serves as a comprehensive debugger for your JSON Web Token implementation. It allows you to decode jwt strings to view the header, payload, and signature claims, facilitating rigorous auth debugging for your web applications.
Inspect your token contents securely. Verify that your authentication service is issuing the correct user roles, expiration times, and issuers. Since the decoding happens entirely in your browser, your sensitive tokens never leave your local machine, ensuring privacy.
Paste your Base64Url encoded JWT string into the text area. The tool will parse the three components color-coded for clarity. You can also view the raw JSON payload to check specific claim values.
Under the Hood
JWT decoding is performed client-side by Base64Url-decoding the three components (header, payload, signature). The JSON segments are parsed and prettified. NOTE: Verification (signature checking) is simulated or requires the user to provide a public key/secret; the tool creates the signature string locally using `crypto-js` (HMAC or RSA) to verify if the input signature matches the computed one, proving message integrity.