JWT Debugger — Decode, Verify & Debug JSON Web Tokens

Paste any JWT to decode its header and payload, check exp/nbf/iat claims against your clock, and verify HS256 signatures with a shared secret — entirely client-side. This free online tool runs entirely in your browser — no data is ever uploaded to a server.

How to Use

1. Paste your token — the three base64url parts split and decode automatically.

2. Check the claims table — iss, sub, aud, exp, nbf, iat, jti are broken out with descriptions.

3. Verify the signature — optional secret key; only runs HS256 verification in-browser.

4. Copy any part — header, payload, hex signature, one click each.

Example

Paste an HS256 token, type the shared secret, and the debugger reports Signature Valid ✓ or Invalid ✗ plus exactly how long the token remains unexpired.

Also check out the live tool at freeq.one/tools/jwt-debugger — part of the FreeQ.One suite of free online tools.