Flutter is an open-source mobile application development SDK created by Google. It is used to develop applications for Android and iOS, as well as being the primary method of creating applications for Google Fuchsia, Flutter widgets incorporate all critical platform differences such as scrolling, navigation, icons and fonts to provide full native performance on both iOS and Android.
FitBit is flutter fitness & Workout app template. So, It is support android and ios both. In this app user can show workout, find workout, chat with trainer etc.