Webhooks are how modern systems actually talk to each other. A payment processor notifies an ERP when a charge settles. A CRM pings a marketing tool when a lead converts. A document signing platform fires off to a contract management system when a signature is captured. At scale, a single mid-market company receives and sends tens of thousands of webhook calls a day. Webhooks are also one of the most common integration attack surfaces. They are HTTP endpoints exposed to the public internet, they accept data that is typically written directly into business-critical systems, and they are often treated as an afterthought by teams that built the “real” API with far more rigor. The security patterns for webhooks are well understood. They are just inconsistently applied. This piece is a short, opinionated guide to the controls that matter, the mistakes that repeat, and what a production-grade webhook receiver looks like.…