A JavaServer Pages (JSP) developer designs, implements and maintains web applications using JSP, a server-side programming technology. They create dynamic web content and user interfaces, integrate JSP with other Java frameworks like Spring and Hibernate, and collaborate with front-end developers to ensure seamless functionality. They also debug and troubleshoot software issues, optimize applications for maximum speed and scalability, and ensure security compliance. Furthermore, they may be involved in testing, documenting the software, and training end-users. Staying updated with the latest industry developments to improve application functionality is also a crucial part of their job.