A Bootstrap developer is responsible for creating, testing, and maintaining websites or applications using Bootstrap framework. They utilize Bootstrap's pre-built classes and interfaces to develop responsive and mobile-first projects efficiently. Tasks may include designing user-friendly interfaces, ensuring cross-browser compatibility, and integrating with other technologies like HTML, CSS, and JavaScript. They also address issues related to website functionality, performance, and navigation. In addition, they may collaborate with designers and backend developers to improve usability, troubleshoot problems, and enhance visual aesthetics. Their work ultimately contributes to a seamless user experience across various device sizes and types.