The Anypoint Connector DevKit is a tool that makes building reusable connectors easier. It uses annotations and code generation to handle boilerplate code needed to integrate connectors with Mule runtime and Anypoint Studio. Connectors allow communication between external resources and Mule applications, transforming data between the two. DevKit abstracts this communication and generates user interfaces, simplifying connector usage. Well-built connectors make app development simpler by handling tasks like pagination and session handling.