The app being studied, LYNX, will use an existing platform called Sex Pro, which is tool that provides a personalized HIV risk score, based on data from several large studies in MSM. The score is on a scale of 1-20, with a higher score representing a higher level of protection, which was highly predictive of HIV risk in a previous study in Black MSM. Sex Pro has been developed into a mobile app with additional features, such as a sex diary to facilitate accurate data collection, HIV/STI testing information and reminders, and access to home HIV/STI testing options and geospatial-based testing site and linkage to HIV care information. The app is being refined to to maximize acceptability among YMSM.