There is a long list of possible frontend frameworks that .NET development teams can choose from. One very exciting candidate is Avalonia UI. Originally launched as a cross-platform alternative to WPF for Windows, macOS and Linux, it now also offers support for mobile platforms (Android, iOS), for the browser (via WebAssembly) and, as a unique selling point, also for embedded Linux. Due to the many supported platforms and the comparable approach to rendering, Avalonia UI could also be called the flutter for .NET developers. Similar to the older WPF, Avalonia UI relies on XAML, it prefers the MVVM pattern, can be adapted to individual visual requirements via styles, has a special focus on performance and is well integrated into current IDEs such as Microsoft Visual Studio and JetBrains Rider. These features make the framework especially interesting for teams that have prior knowledge of WPF or Windows.Forms or are even looking for a migration path for these applications into the cross-platform world. In this session I would like to show what Avalonia UI has to offer today. I will also bring along various sample applications that we can use to discuss the advantages and disadvantages of the framework.