HMAC Generator
Create an HMAC (Hash-based Message Authentication Code) with your secret key — SHA-256, SHA-384 or SHA-512. Everything is computed in your browser; your key never leaves it.
Verify a Signature
Check a given signature (in hex format) against the key and message above.
How to use
- Enter the message and secret key, then select an algorithm.
- Press Generate HMAC — you will get hex, base64 and base64url all three.
- Copy the signature with the Copy button, or check it with the verify tool below.
What is HMAC used for?
HMAC proves a message is authentic — for example signing API requests, verifying webhooks, or creating password reset tokens. Only someone with the secret key can create a valid HMAC.
Frequently Asked Questions (FAQ)
What does the HMAC generator create?
It creates a Hash-based Message Authentication Code from your message and secret key, using SHA-256, SHA-384 or SHA-512.
What output formats are supported?
You get the signature in hex, base64 and base64url, with a copy button for each.
Is my secret key safe?
Yes. Everything is computed in your browser, so your key never leaves it. A verify tool is included below to check a signature.
Is the HMAC generator free?
Yes. It is free with no signup.