HMAC (Hash-based Message Authentication Code) combines a cryptographic hash function with a secret key to verify both data integrity and authenticity. Our free HMAC Generator creates HMAC signatures using the Web Crypto API.
While a regular hash only verifies that data has not been modified, an HMAC also proves that the data came from someone who knows the secret key. This is essential for API authentication, webhook verification, and secure message signing.
Supports HMAC with SHA-1, SHA-256, SHA-384, and SHA-512. Enter your message and secret key, and get the HMAC output instantly. Everything runs in your browser using the Web Crypto API — your key and data are never transmitted.