ToolBirch

HMAC Generator

Keyed message authentication with WebCrypto HMAC.Security & Privacy

HMAC Generator

Compute a keyed Hash MAC with WebCrypto. HMAC verifies both the content and that the holder of the secret produced it.

About this tool

HMAC binds a message to a secret: whoever can produce the tag must hold the key. WebCrypto computes it locally; the secret never leaves the tab.

How to use the HMAC Generator tool

  1. Enter message and secret. Both are required.
  2. Choose the hash. SHA-256, SHA-384 or SHA-512.
  3. Copy the tag. Lowercase hex, ready to compare.

Supported formats

Input

  • Plain text or file input

Output

  • Converted or analysed output

Inputs are validated before anything is processed. Invalid values and unsupported files are rejected with a clear error instead of failing silently.

Frequently asked questions

What is HMAC for?

Verifying that a message came from someone holding the key and was not modified — API signatures, webhooks.

Is this encryption?

No. HMAC authenticates; it does not hide. Combine with encryption if secrecy matters.

Are keys case-sensitive?

Completely — every byte of the secret changes the tag.

Privacy

Everything you enter stays in this browser tab. There is no upload endpoint for tool inputs, no account, and no server-side copy of your text or files. Results are produced locally and disappear when you close the page.

No account is required and no file is ever uploaded. See the privacy policy for details about analytics and the limited data this site stores.

Known limitations

  • Key strength is not assessed; short keys weaken the construction.

Related tools

Other free tools from the same collection.

Password Strength CheckerEstimate password strength from entropy and weak patterns.File Checksum CalculatorSHA digests of a file to verify downloads.File Hash ComparatorCompare two files byte-for-byte via SHA-256.JWT Signature VerifierCryptographically verify HMAC-signed JWTs.