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HMAC Generator

Create HMAC signatures from a message and secret key — computed locally in your browser.

Message and key

The key and message stay in your browser and are never transmitted.

How to use the HMAC Generator

  1. Type or paste the message you want to sign.
  2. Enter the secret key and pick a hash algorithm.
  3. Copy the resulting HMAC signature.

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Frequently Asked Questions

Common questions about the free online hmac generator.

A hash-based message authentication code combines a message with a secret key to produce a signature that proves both integrity and authenticity.
A plain hash anyone can compute, while an HMAC requires the secret key, so it can verify that a message came from someone who holds the key.
HMACs are widely used for API request signing, webhook verification and session tokens.
SHA-256 is the common default. Use SHA-384 or SHA-512 if your platform requires a longer digest.
No. The HMAC is computed in your browser with the Web Crypto API and nothing is transmitted.
HMAC output length depends only on the hash algorithm, not on the message length.
Yes. The generator is fully responsive and works on desktop, tablet and phone.
Yes, it is completely free with no account required.

Last updated: October 10, 2026