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HMAC Generator

Generate HMAC signatures using SHA-256, SHA-1, SHA-384, or SHA-512. Enter a message and a secret key to produce a hex or Base64 authentication code. Powered by the browser's native Web Crypto API —nothing leaves your device.

Developer Tools Runs locally No data sent
HMAC SHA-256 SHA-512 Web Crypto API client-side only
Message
Secret Key
Secret key is required to generate HMAC.
Algorithm
Output
HMAC Result
HMAC-SHA-256 Awaiting input—
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HMAC (Hash-based Message Authentication Code) combines a cryptographic hash function with a secret key to produce a signature. It verifies both the integrity and authenticity of a message —widely used in API authentication (Authorization headers), JWT signing, and webhook verification. This tool uses the browser's native Web Crypto API (crypto.subtle) —your key and message never leave the page.

What is HMAC Generator?

HMAC Generator creates keyed signatures from a message and secret using algorithms such as SHA-256 or SHA-512. It is commonly used for webhook verification, signed API requests, and any workflow where the receiver needs to confirm both integrity and shared-secret authentication.

How to Use HMAC Generator

  1. Paste the message or payload you want to sign.
  2. Enter the shared secret key used by your system.
  3. Choose the HMAC algorithm and output format.
  4. Generate the signature and compare it with the value from your API or webhook flow.

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Understand HMAC Generator ▾
Example
Input Message: hello | Key: secret | Algorithm: HMAC-SHA256
Output Hex: 88aab3ede8d3adf94d26ab90d3bafd4a2083070c3bcce9c014ee04a443847c0b
Common Use Cases
  • Create request signatures for API, webhook, or callback testing
  • Compare HMAC output across SHA-256, SHA-384, and SHA-512 variants
  • Verify whether two systems agree on message signing inputs and secrets
  • Generate HEX or Base64 signatures during development without backend setup
Why Use This Tool
  • Useful for debugging webhook signatures and signed API headers.
  • Lets you compare multiple HMAC algorithms and output encodings quickly.
  • Avoids backend setup when you only need a local signature check.
Frequently Asked Questions
What is the difference between HMAC-SHA256 and plain SHA-256?

SHA-256 hashes data without a key, so anyone can reproduce it. HMAC requires a shared secret key, providing authentication in addition to integrity.

Is SHA-1 HMAC still secure?

HMAC-SHA1 is considered weak for new systems. Use HMAC-SHA256 or HMAC-SHA512 for new implementations.

What does HMAC Generator Online - SHA-256 & SHA-512 Authentication do?

HMAC Generator Online - SHA-256 & SHA-512 Authentication runs entirely in your browser and helps you complete this task without uploading data to a server.

Is HMAC Generator Online - SHA-256 & SHA-512 Authentication free to use?

Yes. This tool is free to use and does not require sign-up.