The Internet of Things (IoT) is a network of physical devices and software entities that interact together for fulfilling an overall objective and thus providing added-value services. Designing such applications by selecting a set of candidate objects and defining how they interact with one another is a difficult and error-prone task. Moreover, IoT applications are not monolithic applications built once and for all. In contrast, they are constantly modified due to removal, replacement, or addition of new objects during the application’s lifetime. In this paper, we present a tool built on top of the WebThings platform, which supports users when they want to dynamically change a running WebThings application. To do so, R-MOZART provides three components for (i) designing the new application using a user-friendly UI, (ii) verifying that this new application respects some consistency properties with respect to the current application, and (iii) deploying this new application in an automated manner. This tool was applied on several smart home applications for evaluation purposes. Video URL: https://youtu.be/bG4oiQUrWSQ