HMAC Generator

About this calculator

This tool generates an HMAC (Hash-based Message Authentication Code) — a cryptographic construction that combines a secret key with a hash function (SHA256, SHA1, MD5, or SHA512) to verify both the integrity and authenticity of a message. Unlike a plain hash, an HMAC can't be reproduced without knowing the secret key, so it proves the message wasn't tampered with and came from someone who holds that key.

Developers use HMACs to sign API requests (many REST APIs authenticate calls this way), verify webhook payloads, protect JWTs, and secure session tokens. Enter your text and secret key and choose a hash algorithm — SHA256 is the current standard for most security-sensitive uses, since MD5 and SHA1 are considered cryptographically weak.