A Bootstrap developer designs and creates user-friendly, responsive websites or web applications using Bootstrap, a popular HTML, CSS, and JavaScript framework. They implement visual and interactive elements that engage users, ensuring optimal functionality and navigation. They also ensure compatibility across different browsers and devices. They often collaborate with back-end developers to integrate their work with server-side logic. Additionally, they are responsible for maintaining, improving, and updating existing sites or applications. They should have a deep understanding of web development principles and best practices, and stay up-to-date with new trends and advancements in web development.