HMAC Generator
Last updated: 2026 · Free online tool
What is HMAC Generator?
Free online tool to generate HMAC-SHA256/SHA512 and verify webhook signatures
How to Use
- 1 Select Mode — Choose generation or verification mode.
- 2 Enter Input — Enter the message and secret key.
- 3 View Result — Copy the generated HMAC or check the verification result (match/mismatch).
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Frequently Asked Questions
HMAC (Hash-based Message Authentication Code) is a method that generates message authentication codes using a secret key and hash function.
HMAC-SHA256 and HMAC-SHA512 are supported, using the Web Crypto API.
Presets for commonly used API signatures like Stripe, GitHub, and Slack webhooks are provided.
Yes, verification mode uses constant-time comparison to prevent timing attacks.
No. All calculations are performed in the browser via Web Crypto API.