Flutter is mostly gaining traction as a mobile app framework. But with the last 1-2 updates flutter allows not only to create almost native feeling apps on ios and android, but also on osx, windows, linux and even the web. The focus of this talk is to show how easy creating cross plattform applications with a single source can be and to highlight advantages/distadvantages and the potential. We will also discuss similar frameworks like react-native and their differences under the hood, with all the pros/cons gathered from real world examples and when they should be used instead. This talk will be half theoretical, half live coding with examples on how to manage cross plattform designs with a single codebase efficiently.