HRV4Training is a science-based mobile platform that helps athletes optimize their goals and prevent overtraining by measuring Heart Rate Variability (HRV) and providing tailored feedback on physical condition. HRV4Training does not require a heart rate monitor, since it is the only app that can accurately assess HRV using the phone's camera. HRV4Training is also the first app that goes beyond simple measurements and provides insights on 1) acute or day to day HRV changes in response to training 2) long term multi-parameter trends to look at the big picture 3) correlations between physiological measurements and annotations 4) training load & injury risk 5) VO2max estimation. All data is processed inside the app in order to provide actionable interpretations that can help optimizing training plans and performance. HRV4Training userbase goes from sport enthusiasts to elite athletes, including coaches & athletes in the NBA, MLS, NFL, MLB, NHL and many Olympic disciplines. Currently, more than 100 000 people across the globe are using HRV4Training to measure physiological data and improve performance. HRV4Training has been among the top 10 best selling apps in more than 4 continents and 30 countries.