Observing the evolution of virtual reality (VR) and augmented reality (AR) applications, a shift from professional users towards a broader public can be noticed in the last few years. This trend creates a demand for intuitive and easy-to-use tools that support people in utilizing VR or AR for their own projects. In this paper we present an open source tool, which we developed to allow non-professional users to project images onto the surface of real-world objects on the fly. We designed a web application that runs both on mobile and desktop devices and therefore can be used in a versatile and flexible manner. We conducted a user study to compare the usability and performance of the mobile and the desktop version of our tool. The results show that users prefer the mobile version for spatially challenging projection tasks.