DEWEX is a server-based environment for developing Web-based experiments. It provides many features for creating and running complex experimental designs on a local server. It is freeware and allows forboth using default features, for which only text input is necessary, and easy configurations that can be set up by the experimenter. The tool also provides log files on the local server that can be interpreted and analyzed very easily. As an illustration of how DEWEX can be used, a recent study is presented that demonstrates the system's most important features. This study investigated learning from multiple hypertext sources and shows the influences of task, source of information, and hypertext presentation format on the construction of mental representations of a hypertext about a historical event.