Flutter is an open-source UI software development kit created by Google. It is used to develop applications for Android, iOS, Windows, Mac, Linux, Google Fuchsia and the web. Flutter apps are written in the Dart language. Flutter is Google’s UI toolkit for building beautiful, natively compiled applications for mobile, web, and desktop from a single codebase. Flutter code is compiled to native ARM machine code using Dart's native compilers. Thus Flutter gives you full native performance on both iOS and Android.