Back to Tools

Crypto ยท Message authentication

Generate HMAC signatures

Type a key and a message, pick an algorithm, get a tamper-evident signature. Native WebCrypto API. Key and message never leave this tab.

Runs locallyNo uploadWebCrypto

Input

Signature

SHA-256
Compute a signature first to see hex and base64 output.

Constant-time comparison on the client. Comparing your computed signature to an expected one on the same machine doesn't replace a real verify-on-the-other-side check, but it's enough for development and debugging.