A Java Server Page (JSP) developer designs, develops, and maintains web-based applications using JSP, a technology that allows software developers to create dynamic content for webpages. They write server-side scripts, incorporate Java code modules to handle business logic, and use HTML or XML for page layout. They also ensure the interoperability of the application with existing systems, troubleshoot issues, and optimize the performance of web applications. In addition, they often collaborate with other team members to understand user requirements, test the application, and improve its functionality. They need to stay updated with the latest JSP and Java developments.