Developer
HMAC generator
Compute a keyed HMAC signature for a message.
Enter a secret key to compute the HMAC.
Computed in your browser with Web Crypto. Nothing is uploaded.
How it works
1
Enter the message
Paste the text you want to sign.
2
Add a key
Provide the secret key and choose the hash — SHA-256, SHA-384 or SHA-512.
3
Copy the signature
Copy the resulting HMAC digest, computed in your browser.
Frequent questions
What is an HMAC used for?
It proves a message came from someone who holds the shared secret key and was not altered in transit — commonly used for signing API requests and webhooks.
How is HMAC different from a plain hash?
A plain hash depends only on the message, so anyone can recompute it. An HMAC also mixes in a secret key, so only holders of the key can produce or verify it.
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