Polling an API on a timer to check whether a website changed its tech stack is wasteful. You burn requests checking domains that have not changed, and you miss changes that happen between your polling intervals. Webhooks solve both problems: DetectZeStack monitors domains on a schedule and pushes notifications to your server only when something actually changes. This guide walks through the full webhook lifecycle: creating a subscription, enabling scheduled monitoring, verifying HMAC-signed payloads, and building a working Slack integration that alerts your team when a competitor switches frameworks, adds a CDN, or drops their analytics provider. Why Monitor Websites for Tech Stack Changes Technology stack changes are leading indicators. A company adding Stripe is about to launch payments. A competitor switching from Heroku to AWS is preparing to scale. A client removing their Content-Security-Policy header just created a security vulnerability nobody noticed. Manual checking does not scale.…