A Foundation by Zurb developer is responsible for creating responsive and user-friendly web designs using the Foundation framework. Their key tasks include developing front-end web applications, implementing interactive UI components, and ensuring cross-browser compatibility. They also optimize web applications for maximum speed and scalability. They work closely with designers and back-end developers to ensure seamless integration of the front-end with the back-end functionality. Additionally, they maintain and improve the Foundation framework by fixing bugs and adding new features. They also need to stay updated with the latest web development trends and technologies.