A Flash/Flex developer is responsible for creating interactive web applications using Adobe's Flash and Flex technologies. They design and implement user interfaces, animations, and multimedia features to enhance user experience. They also ensure the application's functionality across various platforms and browsers. They often work with other team members, like graphic designers and software engineers, to integrate visual design and back-end logic. They need to debug and fix issues, optimize performance, and maintain documentation of their work. Additionally, they must stay updated with the latest technological trends and advancements in Flash and Flex technologies to create innovative solutions.