Writing one codebase which covers two apps (android and iOS) results in writing roughly 50% fewer automated tests.
1 codebase, 2 apps
Developers write just one codebase covering both iOS and Android platforms. Flutter has its own widgets and designs, which means you can have the exact same app UI and business login on two platforms.
Same UI on all platforms
By writing single codebase and using same UI widgets - apps on all platforms look and behave exactly the same without additional costs.
Flutter uses Dart language which was specifically created for performance. It's compiled directly into native code without any additional "bridges" which results in native performance. Flutter's 2D rendering engine "Skia" guarantees 60fps!
2x faster time to market
Flutter has a feature called "Hot Reload" which allows to build and iterate quickly. Update code and see changes almost instantly, without losing state.