The ability of sensing breathing is becoming an increasingly important function for technology that aims at supporting both psychological and physical wellbeing. We demonstrate ThermSense, a new breathing sensing platform based on smartphone technology and low-cost thermal camera, which allows a user to measure his/her breathing pattern in a contact-free manner. With the designed key functions of Thermal Voxel Integration-based breathing estimation and respiration variability spectrogram (RVS, bi-dimensional representation of breathing dynamics), the developed platform provides scalability and flexibility for gathering respiratory physiological measurements ubiquitously. The functionality could be used for a variety of applications from stress monitoring to respiration training.