HMAC and Secret Keys: The Privacy Imperative
HMAC (Hash-based Message Authentication Code) authenticates messages using a secret key. If you send that key to a server-side tool, you've leaked the secret. That's not just bad practice — it's a security vulnerability.
Client-Side HMAC with Web Crypto API
DevUtility uses the browser's native Web Crypto API for HMAC generation. The implementation is identical to what runs in server environments — same algorithms, same security, zero network exposure.
Why FreeFormatter Is Risky for HMAC
FreeFormatter processes your key and message on their server. Even over HTTPS, the server operator can log your secret key. For webhook signatures, API authentication, or any real-world HMAC use, this is unacceptable.
The Rule Is Simple
Never send a secret key to a third-party server. Use client-side tools for all HMAC operations. DevUtility makes this easy and free.