JWT Decoder / Encoder
Debug JSON Web Tokens: decode headers and payloads, verify signatures (HS256), or create new signed tokens. All operations happen in your browser – no secrets are ever sent to a server.
✍️ Encode New JWT (HS256)
🔍 Decode & Verify JWT
📖 How to Use the JWT Tool – Step by Step
- Encode a new JWT – Edit header and payload JSON, provide a secret, then click "Encode HS256". Use "Load Example" to try a sample.
- Decode a JWT – Paste a JWT into the lower textarea and click "Decode Token". Load an example with the button.
- Verify Signature – After decoding, enter the secret key and click "Verify Signature". The tool will tell you if it matches (HS256 only).
- Copy results – Use the copy buttons to grab the encoded token or any part.
💡 Why Use This JWT Tool?
- ✔️ Fully client‑side – your secrets never leave your browser.
- ✔️ Supports HS256 signing and verification using Web Crypto API.
- ✔️ Perfect for debugging JWTs during development.
- ✔️ 100% private – no server logging.
💡 Pro Tip: This tool only supports HS256 (symmetric) signatures. For RS256 or other asymmetric algorithms, use a dedicated library. Always keep your secret keys secure.
🔒 100% client‑side • Your secrets never uploaded • HS256 only • Zero tracking