The complexity of current Web Information Systems represents a challenge when educating the next generation of engineers capable of dealing with all aspects of their life cycle. Network simulators are used in university education to address this challenge and provide students with the necessary comprehensive understanding of the interplay of their inherently distributed system components and the respective protocols at different network layers. However, existing simulators only partially satisfy educational requirements, having limitations in the level of control of educators to focus on selected aspects on the desired conceptual level, support for demonstrations with interventions at runtime, and the flexibility to set up, use, and program the simulators at home and on mobile devices. Thus, we propose WNSWE, a Web-based Network Simulator designed for Web Engineering Education, detailing its client-side architecture, program model, and interactive capabilities. To evaluate WNSWE, we applied it to 26 educational scenarios and report on 3 case studies of employing it for classroom teaching and asynchronous assignments in different university courses and teaching settings, covering a range of topics from basic networking to cloud and security of distributed systems. Furthermore, WNSWE is provided as open educational resource (OER) and we outline our roadmap for its extension.