JWT Decoder & Encoder
Decode, verify, edit and re‑sign JSON Web Tokens – supports HS256, HS384, HS512, and 'none' algorithm.
JWT Toolkit – More Algorithms, Same Security
Now supporting HS256, HS384, HS512 and the "none" algorithm for debugging. All signing and verification happens client‑side using the Web Crypto API via CryptoJS. Your secrets never leave this page.
Edit & Re‑Sign with Any HMAC
Select a new algorithm from the dropdown, change the payload, and click Re‑Sign / Verify. The tool automatically updates the alg field in the header to match your choice, recalculates the signature using the appropriate HMAC length, and gives you a brand new token.
Auto‑Detect & Verify
When you paste a JWT, the decoder reads its alg header and selects the corresponding algorithm for you. It then verifies the signature (if a secret is provided) using the correct HMAC algorithm. For unsupported algorithms (like RS256), you'll see a clear warning.