IoTVIZ is an efficient tool for developing IoT visualization applications based on graphical user interface (GUI). It enables drag-and-drop operations and provides interactive design experience, helping users with less or even no coding experience to quickly develop visualization applications. IoTVIZ has the capability of easily introducing diverse types of data sources, largely reducing the workload of data wash and transformation, and quickly gaining business insights from massive data. IoTVIZ is committed to bringing users a WYSIWYG development experience, and has been widely used in equipment monitoring, traffic planning, logistic tracking and other fields.