What HMAC is used for
HMAC combines a message with a shared secret to create a signature another trusted system can verify.
That's why it shows up so often in webhooks, signed APIs, and partner integrations.
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Browser-based tool
HMAC Generator
Generate keyed HMAC signatures with SHA-1, SHA-256, or SHA-512 for webhook testing, signed requests, and auth debugging.
HMAC uses a shared secret. Keep real production secrets out of screenshots and shared demos.
FAQ
Is this HMAC generator free?
Yes.
Which HMAC algorithms are supported?
The tool supports HMAC-SHA1, HMAC-SHA256, and HMAC-SHA512.
Is my secret key uploaded?
No. Message and secret processing stay in the page.
What is the output format?
The generated signature is returned as a hexadecimal string.
Can I verify a webhook signature with this?
Yes. It's useful for reproducing the expected HMAC so you can compare it with what the provider sent.
Should I use SHA-256 by default?
Usually yes. HMAC-SHA256 is a strong default unless a specific integration requires another algorithm.
How To Use It
Protect real secrets
Even on a local page, production secrets still should not end up in demos, recordings, or shared screens.
Use test keys whenever you can and keep real signing secrets out of casual debugging.
Where HMAC helps developers most
This is most useful when you're checking webhook verification, reproducing signing logic, or comparing browser output with backend output.
It's also handy when vendor docs give you a signing recipe and you want to test it before writing application code.
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