JWT Generator
Build and sign JSON Web Tokens with a custom header, payload, and secret. All signing happens locally — nothing leaves your browser.
Keep your secret private. Never expose it in client-side code or version control.
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How JWT signing works: A JWT is assembled from a Base64URL-encoded header and payload, joined by a dot. The HMAC algorithm then signs this string using your secret key, producing the signature — the third segment. Tampering with the header or payload invalidates the signature.
Signing uses the browser's native crypto.subtle Web Crypto API. Your secret and payload never leave your device.