Formaldehyde is a ubiquitous contaminant in the indoor environment that is both a carcinogen and irritant. The goal of this project is to develop a smartphone-based app for use by citizen scientists or researchers that can be paired with low-cost colorimetric badges for detection of indoor formaldehyde. We conducted both national and geographically-targeted surveys prior to app design. We have subsequently developed the app and conducted a beta test. Surveys of 147 individuals indicated broad public interest in formaldehyde testing using smartphone technology. Testing of the badges indicated consistent change in illumination with increasing formaldehyde exposure. Beta testing indicated users were able to navigate the existing app, and highlighted areas for improvement including incorporation of public surveys. Planned future analysis includes extensive calibration testing and a community-based field test.