An Application Server developer designs, develops, and maintains server-side web applications. They primarily write business logic using server-side languages such as Java, .NET, Python, or Ruby. Their responsibilities include creating database schemas that represent and support business processes, implementing security and data protection, integrating user-facing elements with server-side logic, and optimizing applications for speed and scalability. They also troubleshoot, debug, and upgrade existing systems. Furthermore, they work closely with front-end developers to integrate their work with the application. Understanding user needs and providing software solutions is a key aspect of their job.