Communication systems such as overlay and underlay networks are becoming increasingly complex. Developers may add self-adaptive capabilities to such systems to reduce management effort and to autonomously adapt to changing context. Adding self-adaptive behavior to communication systems, however, is a challenging task due to their distributed and heterogeneous nature. We propose REACT, a model-based runtime environment for adapting communication systems. REACT is available as an open source project and designed to be easy-to-use by practitioners and fellow researchers. In this demo, we follow REACT’s three-step development process and show how a domain expert, who is inexperienced in self-adaptive systems development, can enhance a cloud server management system with self-adaptive behavior easily by using REACT.