JWT Encoder
Build and HMAC-sign a JSON Web Token in the browser.
The reverse of the JWT Decoder: build a JSON Web Token from a header and a payload, sign it with HMAC, and get the signed token back. Everything runs in your browser with WebCrypto — the secret never leaves the page.
Never sign a real token with a production secret in a browser tool — for anything real, sign on your server. none means no signature at all and is rejected by every real verifier.
How to use the JWT Encoder tool
- Enter your jwt encoder in the fields above.
- Adjust any slider or type an exact number — the answer updates as you go.
- Copy the result and close the tab. Nothing you entered was sent anywhere.
About the JWT Encoder tool
Paste a header and a payload, choose HS256, HS384 or HS512, and get a signed token back. The secret is used locally with WebCrypto and is never transmitted anywhere.
Tokens are signed with HMAC, the family of algorithms used for symmetric shared-secret tokens. The "none" option produces an unsigned token for debugging only — every real verifier rejects it.
Everything runs locally in your browser: no data is uploaded, no account is needed, and it works offline once the page has loaded.
Embed this tool
Customize and copy an iframe. Linking back helps both sites.