HMAC Generator
Generate an HMAC (hash-based message authentication code) from a message and a secret key.
About this tool
HMAC combines a message with a secret key so that only someone who knows the key can generate or verify the correct output — used to confirm both the integrity and authenticity of a message, not just detect corruption like a plain hash.
It's how webhooks from services such as Stripe, GitHub and Shopify prove they're genuine, and how many APIs sign requests. To check one, paste the exact request body as the message and the signing secret as the key, then compare the result with the signature header. Secrets are often supplied as hex or Base64 rather than plain text, so choose the matching key format, and pick hex, Base64 or Base64URL output to match the header you're comparing against. Everything is calculated in your browser.