HMAC Hash Generator
Produce a keyed hash (HMAC) of a message using your secret key and SHA-256 or SHA-512, via the browser's Web Crypto API. Both the message and the key stay in your browser, which makes it handy for checking webhook signatures or API auth without a round trip.
- 100% free
- Private & safe
- Runs in your browser
Why use HMAC Generator?
HMAC Generator runs locally using your browser's built-in cryptography, so passwords, keys and hashes are never uploaded or logged.
- Runs instantly in your browser — nothing to install, nothing uploaded.
- Completely free, with no account, no watermarks and no usage limits.
- Handles HMAC-SHA-256; HMAC-SHA-512.
- Enter your message and the secret key.
- Works on any device — desktop, tablet and phone — and is fully keyboard accessible.
How to use HMAC Generator
- Enter your message and the secret key.
- Choose HMAC-SHA-256 or HMAC-SHA-512.
- The signature is computed instantly and shown as hex.
- Copy the HMAC to compare against an expected value.
Examples
- Verifying a webhook signature locally.
- Generating an API request signature for testing.
Supported formats & limits
- HMAC-SHA-256
- HMAC-SHA-512
Limitations
- The security of an HMAC depends on keeping the secret key private.
- Enter the key exactly as your server expects (raw UTF-8 bytes are used).
Frequently asked questions
What is an HMAC?
A hash keyed with a secret, used to verify a message's integrity and authenticity.
Is my secret key uploaded?
No. The key and message stay in your browser and are used only locally.
Which encoding is used for the key?
The key is treated as raw UTF-8 bytes.
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