Most integrations are as simple as Basic Auth—but when Replicate AI required SHA-256 HMAC validation for webhook security, things got complicated fast. In this post, I break down what HMAC validation is, why it matters for API/webhook security, and how we implemented it inside CreatorCon C3 using ServiceNow’s CertificateEncryption API. Along the way, I’ll share the mistakes that tripped me up (like algorithm naming quirks, secret key prefixes, and base64 confusion) and the lessons that finally made it work.

If you’re working with Replicate AI webhooks—or any API that uses HMAC validation—you’ll want this practical walkthrough to save hours of frustration.