๐ HMAC Calculator
Enter a secret key
Enter a secret key and a message to compute an HMAC (keyed-hash message authentication code) live in your browser. Supports SHA-1, SHA-256, SHA-384, and SHA-512. All computation happens via the Web Crypto API and never leaves your browser.
How to use
- Enter a secret key.
- Enter the message to sign.
- Select a hash algorithm.
- The HMAC value is shown automatically in both hex and Base64.
FAQ
What is HMAC?
A mechanism that combines a secret key with a hash function to simultaneously detect tampering and authenticate the sender of a message. Itโs used for signing API requests, verifying webhooks, and similar tasks.
Is this calculation correct?
It has been verified against the official HMAC-SHA256 test vectors defined in RFC 4231, and cross-checked against Node.jsโs standard cryptography library.
How is this different from a plain hash (like SHA-256)?
Anyone can compute a plain hash, but only someone holding the secret key can compute or verify a correct HMAC โ making it suitable for authentication and message-authenticity checks.