A (Java Micro Edition) developer is responsible for creating and maintaining applications for devices with limited processing power like mobile phones or set-top boxes. They use the platform, a collection of Java APIs, to develop these applications. Their tasks include writing code, debugging, testing, and optimizing for performance on targeted devices. They also work on integrating these applications with backend systems. Additionally, they ensure compatibility across different devices and troubleshoot any issues. They often collaborate with other team members, like UI/UX designers and product managers, to deliver a product that meets user needs and business goals.