A Google App Engine developer designs, builds, and manages applications using Google's App Engine platform. This involves writing code, often in languages like Python, Java, or PHP, that runs on Google's scalable infrastructure. They handle tasks ranging from creating user-friendly interfaces, integrating databases, to setting up server-side logic. They also manage data storage solutions and user authentication. They troubleshoot and refine applications based on user feedback and performance metrics. Additionally, they ensure the applications are secure and comply with privacy regulations. Their goal is to develop efficient and scalable applications that meet user needs and business objectives.