In this paper we present a software framework which supports the construction of mixed-fidelity (from sketch-based to software) prototypes for mobile devices. The framework is available for desktop computers and mobile devices (e.g., PDAs, Smartphones). It operates with low-fidelity sketch based prototypes or mid to high-fidelity prototypes with some range of functionality, providing several dimensions of customization (e.g., visual components, audio/video files, navigation, behavior) and targeting specific usability concerns. Furthermore, it allows designers and users to test the prototypes on actual devices, gathering usage information, both passively (e.g., logging) and actively (e.g., questionnaires/Experience Sampling). Overall, it conveys common prototyping procedures with effective data gathering methods that can be used on ubiquitous scenarios supporting in-situ prototyping and participatory design on-the-go. We address the framework's features and its contributions to th...