An canvas developer uses the canvas API to create and manipulate visuals directly on a webpage. They design and implement shapes, images, animations, games, and other interactive graphics, using JavaScript in conjunction with the canvas element. They work to optimize graphic performance and ensure compatibility across various browsers and devices. Furthermore, they may also integrate these graphics with other web technologies like CSS, WebGL, and Web Audio. They often collaborate with UX/UI designers or web designers to enhance the visual aspects and interactivity of a website or web application.