HMAC Generator
Generate HMAC-SHA256 and HMAC-SHA512 signatures from any message and secret key
Creates HMAC signatures on the fly from a message and a secret key, so you can verify message integrity or sign API requests. Everything runs through your browser's built-in Web Crypto API — fast, and with no risk of exposing your key.
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🔒 Everything runs 100% in your browser. Your files and input are never uploaded to any server.
How to use
- Enter the message you want to sign and your secret key.
- Choose a hash algorithm such as SHA-256 or SHA-512.
- Pick an output format — lowercase hex, uppercase hex, or Base64 — and copy the signature.
FAQ
- Could my secret key be exposed over the internet?
- No. Every signature is computed entirely inside your browser via the Web Crypto API, with no data sent to any server.
- What's the difference between plain SHA-256 hashing and HMAC-SHA256?
- A plain hash (SHA-256) is fully reproducible by anyone with the same message, so it only proves data hasn't been tampered with. HMAC mixes in a secret key during the computation, so anyone without that key can never forge a valid signature. That's why HMAC — not a plain hash — is what you should use whenever you also need to authenticate the sender, like signing API requests.
- What's the difference between plain SHA-256 hashing and HMAC-SHA256?
- A plain hash (SHA-256) is fully reproducible by anyone with the same message, so it only proves data hasn't been tampered with. HMAC mixes in a secret key during the computation, so anyone without that key can never forge a valid signature. That's why HMAC — not a plain hash — is what you should use whenever you also need to authenticate the sender, like signing API requests.