The text explores the development and implementation of a webhook system built on top of Knock's existing notification engine, highlighting best practices and design considerations. A webhook is an API endpoint that facilitates real-time data delivery between web applications. In Knock's system, users configure unique URLs to receive event notifications, such as message status updates, which are delivered through user-defined workflows. The design process was informed by industry best practices and documentation from leading companies like WorkOS and Stripe, focusing on user feedback, event categorization, delivery attempts, retries, and security measures. Knock chose to build its webhook system as an extension of its notification engine, leveraging existing infrastructure for scalability and efficiency. This decision allows for the separation of resources for user and system notifications and provides the potential for future feature expansion. While the architecture introduces some complexity, it simplifies maintenance by relying on a single delivery system and offers opportunities for enhanced functionality, such as exposing webhooks for more complex notifications.