HMAC Generator
HMAC (Hash-based Message Authentication Code) combines a cryptographic hash function with a secret key to produce a unique signature for a message. This is used to verify that data has not been tampered with and that it came from someone who knows the shared secret. Enter your message and key, choose a hash algorithm, and get the HMAC in hex or Base64 format — all computed in your browser.
Processed on your deviceNo signup required100% free
256-bit
Message
HMAC Signature
HMAC signature will appear here
Enter message and key, then click Generate
How to Use
- Type or paste the message you want to sign in the Message panel.
- Enter your secret key in the Secret Key field.
- Select the hash algorithm: SHA-256, SHA-384, or SHA-512.
- Choose your output format: Hex or Base64.
- Click Generate to compute the HMAC signature.
- Copy or download the result.
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Frequently Asked Questions
What is HMAC used for?
HMAC is used to verify message integrity and authenticity. It's common in API authentication (e.g., AWS, webhooks), JWT tokens, and secure communication protocols.
How is HMAC different from a regular hash?
A regular hash (like SHA-256) can be computed by anyone. HMAC requires a secret key, so only someone who knows the key can produce or verify the signature.
Is the output deterministic?
Yes. The same message and key will always produce the same HMAC. This is different from encryption, which uses random initialization vectors.
Is my data uploaded?
No. All computation happens in your browser using the Web Crypto API. Your message and secret key never leave your device.