Generate HMAC signatures for API authentication and webhooks
Free online HMAC generator. Create HMAC-SHA256, HMAC-SHA512, HMAC-SHA1, and HMAC-MD5 signatures for API request signing, webhook verification, and data integrity checks.
HMAC (Hash-based Message Authentication Code) is a cryptographic technique that combines a secret key with a hash function to verify both the integrity and authenticity of a message.
HMAC is widely used for API request signing (AWS, Stripe, Shopify webhooks), JWT signatures, and verifying data hasn't been tampered with in transit.
A regular hash only verifies data integrity. HMAC uses a secret key, so only parties who know the key can produce or verify the signature — adding authentication on top of integrity.
HMAC-SHA256 is the most widely used and recommended choice. HMAC-SHA512 offers more security. HMAC-SHA1 and HMAC-MD5 exist for legacy compatibility.
Yes. All computation happens locally in your browser. Your secret key and message are never sent to any server.
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Last updated: January 2025