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HMAC Generator

Generate an HMAC using MD5, SHA-1, SHA-256, or SHA-512.

What Is a HMAC Generator?

The HMAC Generator computes a keyed-hash message authentication code using MD5, SHA-1, SHA-256, or SHA-512. An HMAC combines a secret key with a message using a cryptographic hash function, proving both the integrity of the message and that the sender possessed the key. It is widely used in API authentication and token signing. This free online tool is useful for HMAC generator, HMAC online, keyed hash generator. Common use cases include API signatures, webhook verification, request authentication, and message integrity. It is designed for quick browser-based hashing, encoding, decoding, encryption testing, checksum comparison, identifier generation, and cryptography education. For production security, follow the algorithm's current standards, key-management requirements, and application-specific security guidance.

How to Use This HMAC Generator

  1. 1
    Choose the algorithmSelect the HMAC hash function supported by the tool.
  2. 2
    Enter the secret keyUse the same shared secret expected by the receiving system.
  3. 3
    Enter the messagePaste the exact bytes or text that must be authenticated.
  4. 4
    Generate the HMACCalculate the keyed digest locally in the browser.
  5. 5
    Compare or copyUse the output for a test, signature comparison, or integration check.

Frequently Asked Questions

A plain hash has no key and can be computed by anyone. An HMAC is keyed, meaning only someone with the secret key can generate or verify it. This provides message authentication, not just integrity.
HMAC-SHA256 is the most common and recommended default. HMAC-SHA512 offers a larger output for maximum security, while HMAC-MD5 and HMAC-SHA1 should be avoided for new systems.
HMACs secure API requests (e.g., AWS Signature V4), sign JWTs, and are used in TLS, payment systems, and webhook verification.

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