Regular disinfection of hands and frequently touched surfaces is a critical factor in preventing the spread of infectious diseases and disorders ranging from the common cold and flu to SARS and COVID-19. This activity of frequent disinfection requires a high degree of discipline and leads to increased cognitive and physical effort involved in frequent washing of hands, or the use of a pocket sanitizer. We present an open-source, wearable sanitizer that provides just-in-time, automatic dispensing of alcohol to the wearer’s hand or nearby objects using sensors and programmable cues. We systematically explore the design space for wearable sanitizers aiming to create a device that not only seamlessly integrates with the user’s body and behavior but also frees their physical and mental faculties for other tasks. With these insights, we demonstrate our prototype and present the design process, device characterization, and our efforts for open-sourcing this project.