AUTH · SECURITY · DEVELOPER TOOL

JWT Debugger Pro

Decode JSON Web Tokens instantly in your browser. Inspect header, payload, expiry, and verify HS256 signatures — 100% private, local‑first.

keyJWT Token

terminalDecoded Output

Decoded information will appear here...

info All decoding and verification happens locally. Your token and secret never leave this browser tab.

verified_user

100% Private & Secure: The token is processed entirely in your browser. No data is ever sent to any server.

How to Use This Debugger

1

Paste Your JWT

Copy the complete JWT string from your Authorization header or storage and paste it into the text area.

2

Click Decode

The tool automatically splits the token, decodes the header and payload, and displays their contents in a readable JSON format. It also detects if the token has expired.

3

Verify Signature (optional)

If your token uses HMAC (HS256), enter the shared secret and click "Decode JWT" again to check the signature validity.

Frequently Asked Questions

JSON Web Token (JWT) is an open standard (RFC 7519) that defines a compact and self‑contained way for securely transmitting information between parties as a JSON object. It is often used for authentication.

Absolutely not. All decoding and verification happens locally in your browser. Your token is never uploaded or stored.

Currently this tool supports HMAC‑based signatures (HS256, HS384, HS512). For RSA/EC signatures, use a library like jsrsasign or an online JWT verification service.

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