DevToolKit

HMAC Generator

Generate secure HMAC codes using SHA-256, SHA-512, BLAKE3, and more. 100% private, client-side generation with support for Hex and Base64 inputs.

Configuration

Generated HMAC

Awaiting Key & Message
Length: 0 characters

Implementation

Node.js
// Enter values to see snippet
Python
# Enter values to see snippet
Zero-Knowledge Generation

Your secret key and message are processed strictly within your browser's local sandbox. We never transmit your data or keys to any server.
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How to Use

The HMAC Generator allows you to create secure Message Authentication Codes using a secret key and a cryptographic hash function.

How to use this tool

  1. Select Algorithm: Choose a hash function from the dropdown (e.g., SHA-256 for standard security or BLAKE3 for high performance).
  2. Enter Secret Key: Provide your private authentication key. You can also click "Generate" to create a cryptographically strong random key.
  3. Enter Message: Paste the text or data you wish to sign.
  4. Verify Output: The HMAC will be calculated instantly in your browser. You can view the result in hex format.
  5. Integration Snippets: Look at the bottom of the page for ready-to-use implementation code for Node.js and Python.

About This Tool

What is an HMAC?

HMAC (Hash-based Message Authentication Code) is a specific type of message authentication code involving a cryptographic hash function and a secret cryptographic key. It is used to simultaneously verify both the **data integrity** and the **authenticity** of a message.

Any change to the message or the secret key will result in a completely different HMAC, making it an essential component of secure API authentication, webhooks, and session management (like JWTs).

Why Use This Tool

Safe & Secure by Design

Handling authentication keys requires extreme care. Most online tools send your secret keys to their servers for processing, which is a major security risk. Our generator runs **100% client-side**. Your keys and messages never leave your machine, ensuring that your secrets remain truly secret.

FAQ

What is an HMAC?
HMAC (Hash-based Message Authentication Code) combines a cryptographic hash function with a secret key to produce a fixed-size authentication tag. It verifies both data integrity and authenticity — if either the message or key changes, the HMAC output changes completely.
Which algorithm should I use?
SHA-256 is the most widely used and recommended for general purposes. SHA-512 offers higher security margins for sensitive applications. BLAKE3 is the fastest option and suitable for high-throughput scenarios. Avoid MD5 and SHA-1 for new applications as they have known weaknesses.
Is my secret key safe?
Yes. All HMAC computation happens locally in your browser using the Web Crypto API. Your secret key and message data never leave your device — no network requests are made during generation.
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