An Interface Developer is responsible for designing and implementing user interfaces for websites or software applications. They work closely with UX/UI designers and backend developers to ensure a seamless user experience. Their tasks include creating wireframes, prototypes, and final designs, coding the visual interactions, and testing the interface for bugs or usability issues. They use languages like HTML, CSS, JavaScript, and tools like React or Angular. They also ensure the interface is responsive, accessible, and compatible across different browsers and devices. User feedback is crucial for them to improve the interface's functionality and usability.