Adequate tool support is a crucial factor of success for a software development method or technique. In this paper, we present the MagicUWE tool, that supports systematic design of web applications with the UML-based Web Engineering (UWE) approach. It provides assistance to the designer for the modeling activities using the UWE profile and the semi-automatic generation of models. MagicUWE is implemented as a plugin for the CASE tool MagicDraw. Focus of the development of the plugin was the usability, adaptability and extensibility of the tool.