HMAC Generator
Keyed hashes for webhook signatures.
HMAC proves a message came from someone holding the shared secret — it is how webhook signatures (GitHub, Stripe, Slack) are checked. Computed locally with the Web Crypto API; your key never leaves this tab.
About this tool
Compute HMAC-SHA-1/256/384/512 of a message with a secret key using the Web Crypto API — the same signatures GitHub and Stripe webhooks use. Never uploaded.
It runs completely in your browser — no input is sent anywhere, and this page loads no ads or third-party scripts, so it is safe to use with data you would not paste into a hosted service.