Avalonia is a free and open-source[3][4] .NET cross-platform XAML-based UI framework [5] inspired by WPF/UWP and distributed under the MIT License.

[9] It enables development of cross-platform applications using any .NET language, including C#, F#[10] and VB.NET for Windows, Linux, macOS, iOS, Android and WebAssembly.

[11][12] Avalonia supports multiple renderers, including Direct2D and Skia Graphics Engine,[13] allowing it to operate on a broad range of platforms.

Avalonia draws its entire UI,[14] mirroring the approach taken by Flutter.

Avalonia, originally named Perspex,[15] was first developed by Steven Kirk, with its initial commit made on 5 December 2013.