A MIDP (Mobile Information Device Profile) developer specializes in creating applications for mobile devices using the Java ME platform. They design, build, test, and maintain these apps to ensure optimal performance and user satisfaction. They utilize MIDP libraries for creating user interfaces, networking, storage, and other functions. They also have to consider the limitations of mobile devices such as memory, processing power, and screen size. Moreover, they must comply with the security policies defined in MIDP and ensure that the applications are compatible across various devices. They often work closely with other developers, testers, and stakeholders throughout the development process.