HMAC Generator
Generate an HMAC for a message with a secret key.
Quick answer: enter your details below and click Generate HMAC — your result appears instantly, right here in your browser. Nothing you enter is uploaded or stored.
H
Developer
Enter your details below.
How to use
- Enter the secret key.
- Enter the message to sign.
- Choose the algorithm and click Generate HMAC.
About this tool
An HMAC combines a secret key with a message to produce a fingerprint that only someone holding the key can reproduce, which is how receivers check that a message is genuine and unaltered. This tool signs with the browser's WebCrypto API using SHA-256 or SHA-1, and the key and message never leave your device. Keep the key secret: anyone with it can forge a valid HMAC.
Frequently asked questions
What is the difference between a hash and an HMAC?
A plain hash needs no key, so anyone can compute it; an HMAC needs the secret key, so it also proves the message came from a key holder.
Should I use SHA-256 or SHA-1?
Prefer SHA-256: SHA-1 is weaker and is kept here only for checking older systems that still require it.