HMAC Calculator
Developer · v1.0.0 · runs fully in the browser, data never leaves your device
Key format
Many services hand out keys as Base64 or Hex strings — pick the wrong format and every signature will mismatch.
Output format
HMAC-SHA-256
—HMAC-SHA-512
—HMAC-SHA-1
—HMAC-SHA-384
—Signature verification
Paste the signature the other side sent and we'll tell you which algorithm matches — both Hex and Base64 forms are accepted, and case plus whitespace are ignored.
Everything is computed locally; the key is never sent to any server. Note that HMAC differs from "hash(key + message)" — the latter is vulnerable to length-extension attacks, so don't substitute string concatenation for HMAC.