🔏 HMAC SHA-256

Compute HMAC SHA-256 of a message with a secret key.

HMAC

Sponsored
How it works

How it works

HMAC (Hash‑based Message Authentication Code) uses a cryptographic hash (SHA‑256) together with a secret key to authenticate messages.

  • The key is normalized to the hash block size and combined with inner/outer pads (ipad/opad).
  • Compute H(key ⊕ opad || H(key ⊕ ipad || message)), where H is SHA‑256.
  • Verification recomputes the same MAC and compares in constant time.

Use‑cases: API request signing, webhooks, and integrity/authentication of messages between parties sharing a secret.

Privacy & Security

Secret never leaves browser.

Sponsored
Accuracy, Limits & Tips

No streaming; loads whole message into memory.

Examples
  • Key: secret, Message: hello world.

Related tools

Sponsored
You may also like

Looking for broader guides and best practices? Visit the ToolsAreUs Blog for indexes (like the full tool list) and articles (e.g. secure password generation).