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JWT Signer — Sign a Token Locally With Your Own Secret

Enter a payload and your HMAC secret to produce a signed JWT computed entirely in your browser using the Web Crypto API — your secret key never leaves the page, which matters because a signing secret is exactly the kind of value you do not want passing through a third-party server.

How to use JWT Signer

  1. Enter your payload claims.
  2. Enter your HMAC secret and choose the algorithm.
  3. Sign the token.
  4. Copy the resulting JWT.

Frequently asked questions

Is my secret sent anywhere?
No. Signing runs entirely client-side with the Web Crypto API, so the secret never leaves your browser.
HS256, HS384 or HS512 — which should I use?
HS256 is the most widely supported and sufficient for most cases; HS384/HS512 offer a larger security margin at negligible extra cost if your verifying system supports them.
How is this different from JWT Generator?
They overlap in function — this page focuses specifically on the signing step with your own secret; JWT Generator additionally helps you build the claim set from scratch.

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