Abstract : The development of smart spaces is a complex and challenging task. The choice of suitable sensors and actuators to deploy in these physical testbeds is difficult without experimentation. Moreover, several challenges still remain in improving and testing new fields of application based on Web of Things (WoT). In this paper, we present UbiUnity, a dynamic visual simulator environment which can be used during the design phase of smart spaces. Our approach allows to define web services for devices (WSD) associated to 3D virtual shape in the simulated environment. These WSD are defined by combining simple actions in the virtual environment allowing the researchers to focus on the definition of new algorithms or middleware to manage the smart space. Moreover, UbiUnity can dynamically create these WSD during the execution of the simulation with respect to the fluidity of the graphics rendering.