A JavaServer Faces (JSF) developer designs and develops web applications using JSF, a Java-based web application framework. They construct user interfaces with JSF tags, manage user sessions, and handle events. They work with other Java technologies like Enterprise JavaBeans (EJB) and Java Persistence API (JPA) for business logic and data persistence respectively. They also integrate JSF applications with other systems and perform testing to ensure functionality and efficiency. They troubleshoot and resolve issues, and may also provide documentation and training to users. Their goal is to create robust, efficient, and secure web applications.