Free Online HMAC Generator

Calculate Hash-based Message Authentication Codes with secure custom secrets.

Calculate Message Authentication Codes (HMAC)

HMAC (Hash-based Message Authentication Code) is a cryptographic signature algorithm used to verify data integrity and message authenticity. It combines a cryptographic hash function (like MD5, SHA-256, or SHA-512) with a secret key.

Our free online HMAC generator helps verify API integration requests:

Algorithm Support: Choose between MD5, SHA-1, SHA-224, SHA-256, SHA-384, or SHA-512 hash functions.
HMAC Output: Outputs clean, lowercase hexadecimal signature outputs.
Secure Logic: Runs locally, ensuring secret keys are never transmitted.

Key Benefits & Features

✓

Multi-Algorithm Presets

Supports standard SHA-256, SHA-512, MD5, and SHA-1 HMAC formats.

✓

Custom Secret Keys

Validates integrity using secure message keys.

✓

Secure Cryptography Sandbox

Calculations occur locally, securing API secrets.

How to Use the HMAC Generator Step-by-Step

This utility runs entirely inside your browser using client-side JavaScript. We prioritize your security: none of your inputted text is logged or stored.

1
Enter the raw message string in the input field.
2
Enter the secret key in the designated key field.
3
Select the hashing algorithm and copy the resulting HMAC string.

Practical Examples

Input Example

Message: hello, Key: secret, Algorithm: SHA-256

Expected Output

HMAC: 88a5b99b5a76b0cf9915a77df48987487216a9089f2a2455c1b5042217c093a1

Frequently Asked Questions (FAQ)

What is an HMAC?▼

An HMAC is a cryptographic authentication code that verifies both the data integrity and the authenticity of a message using a shared secret.

Why use HMAC instead of a standard hash?▼

Standard hashes are vulnerable to length extension attacks. HMAC incorporates a secret key to prevent unauthorized tampering.

How is HMAC used in web APIs?▼

Web clients compute an HMAC signature of their request payload using an API secret key. The server calculates it on arrival and compares results to authenticate requests.

Explore category: Security & Cryptography

Ready to boost your productivity?

Browse our full list of free security & cryptography and make your daily content, coding, or math tasks easier.

View All Security & Cryptography