Sign HMAC JSON Web Tokens (HS256/HS384/HS512) locally using Web Cryptography API.
Execution runs 100% locally inside the browser sandbox using HTML5 Canvas, Web Cryptography Subtle API, and Web Workers. Zero egress.
Zero network latency. Operates completely offline with zero dependencies on third-party backend servers or cloud services.
Built according to official RFC specifications, cryptographic test vectors, and enterprise-grade data transformation standards.
Select HS256, HS384, or HS512 and enter your secret key.
Customize the JSON payload object (sub, exp, custom claims).
Copy the compact base64url signed JWT string.
No, HMAC signing uses the W3C Web Crypto Subtle API locally in your browser memory.
HS256 (HMAC-SHA256), HS384 (HMAC-SHA384), and HS512 (HMAC-SHA512).
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