A CocoaPods developer is responsible for managing library dependencies in iOS and macOS projects. They use the CocoaPods dependency manager to automate the integration of external libraries, saving time and reducing errors. They write Podfiles to specify these dependencies and versions, ensuring consistency across development environments. They also manage updates, keeping libraries current without breaking project functionality. Additionally, they may create and distribute their own Pods, reusable modules of code that can be shared with other developers. Essentially, a CocoaPods developer enhances the efficiency and reliability of application development in the Apple ecosystem.