HMAC Calculator

Calculate HMAC values for text, local files, or URLs using SHA-256, SHA-512, SHA-1, MD5, and other hash algorithms in your browser. Read more

HMAC calculator online

HMAC (Hash-based Message Authentication Code) combines a cryptographic hash with a secret key. Use this page when you need an HMAC generator or HMAC calculator for text, a local file, or a URL, including common searches such as HMAC SHA256 online, HMAC SHA512, HMAC SHA1, and HMAC MD5.

This page focuses on widely used HMAC algorithms: SHA-256, SHA-512, SHA-384, SHA-224, SHA-1, and MD5. Other hash functions can also be used with HMAC in theory, but RIPEMD, MD2, MD4, and similar legacy algorithms are uncommon for general HMAC workflows. Use those algorithm-specific hash pages when you need legacy compatibility.

A plain hash verifies that bytes match an expected digest. HMAC adds a secret key, so someone without the key cannot produce the same value for a changed message. HMAC authenticates integrity with a shared secret; it does not encrypt data and cannot hide the message contents.

Calculation stays in your browser. Local files and secret keys are not uploaded to this site.

How to calculate HMAC-SHA-256

  1. Keep Source set to Text, or switch to File / URL when calculating the HMAC for raw bytes.
  2. Enter the message. For Text source, choose the input encoding that matches those bytes (UTF-8 by default).
  3. Select Algorithm HMAC-SHA-256 (the default).
  4. Enter the secret key and its key encoding (UTF-8, Hex, or Base64).
  5. Choose Hex or Base64 for the MAC output.
  6. Calculate and compare the full result with the expected HMAC.

Reproducible example

  • Algorithm: HMAC-SHA-256
  • Message: The quick brown fox jumps over the lazy dog
  • Key: key (UTF-8)
  • Output: Hex

Expected HMAC-SHA-256:

f7bc83f430538424b13298e6aa6fb143ef4d59a14946175997479dbc2d1a3cd8

Hash versus HMAC

Use a plain hash page when you only need a digest for integrity or content addressing. Use HMAC when a shared secret should bind the digest to an authenticating party.

This calculator is not a password-storage KDF. For password hashing or key derivation, prefer Bcrypt, PBKDF2, or HKDF when those fit the protocol.

  • SHA-256 text hash, including optional HMAC on that page
  • SHA-256 File Checksum for file digests
  • MD5 (legacy; prefer SHA-256 or stronger algorithms for new work)

Choose a strong, secret key for real authentication. Empty keys are technically valid for testing, but they are not suitable for production secrets. Do not put production keys into share URLs.

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Output
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Key