Microsoft unveils Reactor: WinUI apps can be written in pure C#, no XAML

Microsoft has introduced Microsoft.UI.Reactor, an experimental framework that brings the MVU pattern, familiar from React, SwiftUI and Jetpack Compose, to WinUI. The UI is described in plain C# code, with no XAML files, code-behind or view models, while the screen still shows real WinUI controls. A simple counter app fits in a single file and runs directly on .NET 10. The package includes flexbox layout built on a port of Yoga, navigation, theming, a DataGrid and more than 60 analyzers that catch mistakes as you type. This is not a replacement for XAML and MVVM: the two approaches will live side by side and work together in the same app. The code is open source under the MIT license, and Microsoft asks developers to say honestly where the approach breaks down: while the framework is experimental, the syntax may still change.