HMAC Signature Generator
Generate HMAC-SHA256 and HMAC-SHA512 signatures from text with a secret key. Free, instant, 100% client-side — your data and keys never leave your browser.
Frequently Asked Questions about HMAC Generation
How do I generate an HMAC signature online?
Enter your message text and secret key, select HMAC-SHA256 or HMAC-SHA512, and the HMAC signature is generated instantly. No server involved — everything runs in your browser.
What is HMAC and what is it used for?
HMAC (Hash-based Message Authentication Code) is a mechanism for verifying data integrity and authenticity. It combines a hash function with a secret key to produce a signature that can be used to verify API requests, tokens, and message integrity.
What is the difference between HMAC-SHA256 and HMAC-SHA512?
HMAC-SHA256 produces a 256-bit (64-character hex) signature, while HMAC-SHA512 produces a 512-bit (128-character hex) signature. SHA-512 offers more security but SHA-256 is sufficient for most applications.
Is this HMAC generator secure?
Yes, all HMAC computation happens 100% client-side using CryptoJS. Your secret key and data never leave your browser and are never sent to any server.
Can I use HMAC for API authentication?
Yes, HMAC is commonly used for API authentication (e.g., AWS Signature, Stripe webhooks). Generate your HMAC signature here and compare it with the expected value to verify requests.
What output formats are available?
The tool outputs HMAC signatures in hexadecimal (lowercase) and Base64 formats. You can copy either format with one click.