A jsoup developer is responsible for using the jsoup library in Java programming to extract and manipulate data stored in HTML format. They parse HTML documents, scrape data from websites, and manipulate HTML elements, attributes, and texts. They handle HTTP connections, cookies, and sessions, and implement data extraction and web crawling. They also sanitize user-generated content against XSS attacks. Their role involves dealing with real-world HTML, including dirty and malformed documents. They ensure the smooth transition of data from websites to applications, enabling the retrieval of specific website content, and the creation of new data by manipulating HTML elements.