HMAC Generator

Generate HMAC-SHA256 digests from secret and message.

What this tool does

Generate HMAC-SHA256 signatures for request signing, webhook verification tests, and secure message integrity checks.

Tool interface

Input

Output

Example input

super-secret-key

{"event":"invoice.paid","id":"evt_123"}

Example output

2a19052d5c9e4c42f96b59df3d3d75a1f4d7f033e24b0e8fce8f4e40a89c7a3d

Step-by-step instructions

  1. Paste the secret key in the first block.
  2. Leave a blank line, then paste the message in the second block.
  3. Click Transform to generate the HMAC digest.

Common use cases

  • Debugging request payloads and encoded values quickly.
  • Generating development data and identifiers.
  • Validating text, URLs, timestamps, and structured content.

Useful for quickly verifying signatures when debugging webhook callbacks and signed API request flows.

Common mistakes to avoid

  • Not separating secret and message with a blank line.
  • Using a different secret than the source system.
  • Comparing hashes generated from message strings with different whitespace.

Frequently Asked Questions

Which algorithm does HMAC Generator use?

This tool generates HMAC using SHA-256.

How do I provide secret and message?

Use two blocks separated by one blank line: secret first, message second.

Can I verify webhook signatures with this?

Yes. Generate the digest from the same secret and raw payload for comparison.

What input format does HMAC Generator expect?

Use the format shown in the example input on this page.

What does HMAC Generator output?

It returns transformed output you can copy or download as `hmac.txt`.

Why might HMAC Generator return an error?

A common issue is: Not separating secret and message with a blank line.

Does HMAC Generator run in the browser?

Yes. Transformations are designed for in-browser usage so you can test and iterate quickly.

Can I copy or download results from HMAC Generator?

Yes. You can copy the result or use the download action when file output is available.

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