A CanJS developer is responsible for building and maintaining web applications using the CanJS JavaScript framework. They use this framework to structure their code, create reusable components, manage the application state, and interact with APIs. They also ensure the application remains efficient, scalable, and easy to test. CanJS developers often work as part of a team, collaborating with other developers, UX designers, and stakeholders to deliver high-quality software solutions. They must be skilled in JavaScript, understand the principles of software design, and be familiar with web technologies such as HTML, CSS, and RESTful services.