A CanvasJS developer specializes in using the CanvasJS library to create interactive and dynamic data visualizations. They design and implement charts and graphs that are engaging, easy-to-read, and responsive across different devices. They work with both frontend technologies and backend data sources to fetch, manipulate, and visually display data in real-time. Their tasks might include creating dashboards for business metrics, plotting complex scientific data, or visualizing user behavior data. They continuously optimize performance and troubleshoot issues to ensure smooth user experience. They also collaborate with other team members to integrate these visualizations into larger applications.