Free Online Tool

HMAC Generator

Create HMAC authentication codes with various hash algorithms.

HMAC Generator

Generate Hash-based Message Authentication Codes for data integrity and authentication

Algorithm

Output Encoding

Hexadecimal

Base64

Message / Data

Length: 0 characters

Secret Key

Keep this key secret. It's used to generate and verify the HMAC.

Generated HMAC

Example Messages

Click any example to test HMAC generation

The quick brown fox jumps over the lazy dog

Secret: key

Classic pangram with simple key

Hello World

Secret: my_secret_key_123

Simple message with secure key

{"user":"john","action":"login"}

Secret: api_secret_token

JSON payload authentication

How to Use HMAC Generator

Enter both a message and a secret key.
Select SHA-256 and Hex to reproduce the default examples, or choose another supported digest/encoding.
Read the keyed digest generated in real time.
Use Verify mode with the same message, secret, algorithm, and encoding to compare an expected HMAC.

HMAC combines a secret key with a cryptographic hash in a defined inner/outer construction. It authenticates a message; it does not encrypt it.

Default HMAC-SHA256 in hex:

Message: The quick brown fox jumps over the lazy dog Secret: key

Output:

f7bc83f430538424b13298e6aa6fb143ef4d59a14946175997479dbc2d1a3cd8

Default HMAC-SHA256 in hex:

Message: Hello World Secret: my_secret_key_123

Output:

1a8b4183ea8cd3ed4204470fea44a69a7a23736edd907fd713c4d55b65a7ccde

All processing happens in your browser. No data is sent to servers.

No registration, no limits, completely free to use.