Cryptography

HMAC Calculator

Compute or verify HMAC-SHA-256/384/512 with a UTF-8 or Hex key. Runs entirely in your browser via Web Crypto.

Free to use — no sign-up or login.

Runs entirely in your browser; input is not sent to our servers.

Messages, keys, passwords, plaintext, ciphertext, and files are never stored in localStorage, history, or analytics payloads.

Secure

HMAC (Hex)

HMAC (Base64)

Verify result

This free HMAC Calculator covers Compute or verify HMAC-SHA-256/384/512 with a UTF-8 or Hex key. Runs entirely in your browser via Web Crypto.

Enter the HMAC Calculator fields, then read the output. Cryptography calculators on this site keep the formula visible beside the form, with no account required.

Using the HMAC Calculator

Compute or verify HMAC-SHA-256/384/512 with a UTF-8 or Hex key. Runs entirely in your browser via Web Crypto. Typical inputs are Algorithm, Key format, Key and Message. How it works beside the form states the identity the HMAC Calculator applies.

FAQ

How do I use the HMAC Calculator?

Open the HMAC Calculator, fill Algorithm, Key format, Key and Message, and read the result. Enter a shared secret key (UTF-8 or Hex), the message, and HMAC-SHA-256/384/512. Generate produces Hex and Base64 tags; verify mode compares your pasted expected tag with a constant-time byte check so timing does not leak mismatches.

What formula does the HMAC Calculator use?

The HMAC Calculator uses the identity in How it works. In words: Enter a shared secret key (UTF-8 or Hex), the message, and HMAC-SHA-256/384/512. Generate produces Hex and Base64 tags; verify mode compares your pasted expected tag with a constant-time byte check so timing does not leak mismatches.

Sources