Use HMAC Generator online for free. No installation, no signup — works directly in your browser.
100% free, no signup required. Works entirely in your browser.
Open HMAC GeneratorType the message to sign.
Enter the secret key.
HMAC signature is generated.
HMAC (Hash-based Message Authentication Code) combines a cryptographic hash function with a secret key to produce a signature that verifies both data integrity and authenticity. Unlike plain hashing, HMAC ensures that only parties with the shared secret key can generate or verify the signature. It is widely used in API authentication, webhook verification, and secure communication protocols.
A plain hash like SHA-256 only verifies data integrity — anyone can compute it. HMAC adds a secret key to the hashing process, providing both integrity verification and authentication. This means an attacker cannot forge a valid HMAC without knowing the secret key, making it suitable for verifying API requests, cookies, and message authenticity.
SHA-256 is recommended for most use cases, providing an excellent balance of security and performance. SHA-512 offers higher security margins for critical applications. Avoid MD5 and SHA-1 for HMAC in new implementations due to their weakened hash functions, although HMAC-MD5 is technically still considered secure for authentication purposes.
