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HMAC Generator

Crypto & Security

Generate HMAC signatures for API authentication. Free, private — all processing in your browser.

Webhook verification — Stripe, GitHub, Slack sign payloads with HMAC-SHA256
JWT signing — HS256 = HMAC-SHA256, HS512 = HMAC-SHA512
API authentication — AWS Signature V4 uses HMAC-SHA256
Message integrity — Verify data hasn't been tampered with

How to use

  1. 1. Enter or paste your data in the input area above
  2. 2. Adjust settings or options as needed
  3. 3. Click the action button or see real-time results
  4. 4. Copy the result with the copy button

All processing happens in your browser. Nothing is sent to any server.

About this tool

Generate HMAC (Hash-based Message Authentication Code) signatures for API authentication and webhook verification. Our tool supports HMAC-SHA256, HMAC-SHA384, and HMAC-SHA512 algorithms. Enter a message and a secret key to generate the HMAC signature. HMAC combines a cryptographic hash function with a secret key to provide both data integrity and authentication — the recipient can verify that the message was not tampered with and was sent by someone who knows the secret key. Used extensively in API authentication (AWS Signature V4, Stripe webhooks, GitHub webhooks), JWT signing (HS256 = HMAC-SHA256), and secure message verification. All computation uses the Web Crypto API in your browser.

FAQ

Is the HMAC Generator free to use?

Yes, completely free. No signup, no premium tiers, no hidden costs.

Is my data safe when using the HMAC Generator?

All processing happens in your browser. Your data never leaves your device.

Does the HMAC Generator work on mobile?

Yes, fully responsive. Works on smartphones, tablets, and desktops.

Do I need to install anything?

No. It runs entirely in your web browser. Just open the page and use it.

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