HMAC Generator
Create HMAC-SHA256/384/512 message authentication codes from a secret key.
Private by design. Every tool runs 100% in your browser — your code, text, and tokens never leave your device. Nothing is uploaded or stored.
Hex signature
Result appears here.
Frequently Asked Questions
What is HMAC used for?
HMAC proves both integrity and authenticity of a message using a shared secret — a receiver with the same key can confirm the data was not altered and came from you.
SHA-256 vs SHA-512 for HMAC?
Both are secure; SHA-512 is marginally stronger and faster on 64-bit systems. Use SHA-256 unless you have a specific compliance reason for 512.
Is HMAC the same as hashing a secret + message?
No. Naively concatenating secret+message is vulnerable to length-extension attacks; HMAC applies the hash twice in a specific construction to avoid that.