An Apache Felix developer works with the Apache Felix framework, an open source implementation of the OSGi (Open Services Gateway initiative) specification. They design, develop, and maintain OSGi bundles, ensuring smooth and efficient interaction between different components. They are responsible for developing modular, dynamic applications in Java, enabling component deployment, versioning, and service registry. They also troubleshoot and resolve issues regarding the compatibility and interoperability of different modules. Furthermore, they work on enhancing system performance, manage updates and upgrades, and ensure the system's compliance with defined standards and specifications. They collaborate with other developers to create user-friendly interfaces and improve user experience.