A Coffeescript developer designs, tests, and implements software solutions using Coffeescript, a programming language that transcompiles into JavaScript. They typically work on the client-side of web development, creating interactive elements, enhancing website functionality, and improving user experience. They collaborate with frontend and backend developers to integrate their work with other parts of the web application. Their tasks also include debugging, maintaining the codebase, optimizing performance, and ensuring the website is responsive and compatible across different browsers and devices. They need to remain up-to-date with new technologies and practices, and often participate in code reviews to ensure quality control.