AvaloniaUI: Create Multi-Platform Apps with .NET

Original Article ↗ Hacker News Discussion ↗

AvaloniaUI is presented as a cross‑platform UI framework for .NET that targets Windows, macOS, Linux, web, and increasingly mobile, using Skia for rendering and XAML for layout—making it especially attractive for teams with WPF or Xamarin.Forms backgrounds. Commenters highlight its strengths in desktop scenarios, active open‑source development under the MIT license, and a viable business model via a commercial WPF-compatible product (XPF), with several notable companies already using it in production. Concerns center on immature mobile support, non‑native look and feel, performance issues such as startup time, CPU and memory usage, and a still‑growing ecosystem of controls compared to more established toolkits.

Ecosystem & Controls

  • Main concern: smaller ecosystem vs mature native stacks (e.g., fewer ready-made controls like maps, charts, date pickers).
  • Counterpoint: several charting/mapping libraries and other controls already exist in the Avalonia/.NET ecosystem.
  • Some users highlight availability of community collections (e.g., “awesome” lists) and third‑party libraries.

Desktop vs Mobile Focus

  • Avalonia is widely seen as desktop‑first; mobile support exists but is described as “coming,” “not production‑ready,” or less polished.
  • Controls like TextBox can feel desktop‑oriented on mobile.
  • Some argue you must redesign UI per form factor anyway; others want a “mobile‑first, desktop‑second” cross‑platform toolkit and see that as still unmet.

Performance, Rendering, and UX

  • Uses Skia; compared conceptually to “Flutter for .NET.”
  • Mixed reports: some call it fast (especially with Native AOT and compiled bindings), others report:
    • High idle CPU usage, especially on macOS and with animations.
    • Slow startup and relatively high memory use.
    • Non‑native text behavior (e.g., undo/redo granularity) and “off” font rendering.
  • Broader debate over Skia’s CPU use, GPU acceleration, and the general slowness of modern 2D UI stacks, with comparisons to browsers, games, and alternative renderers.

Production Use & Licensing

  • Multiple companies and products use Avalonia in production (including some well‑known names).
  • The framework itself is MIT‑licensed, fully open source, with no paid “pro” tier or hidden feature gates.
  • Revenue model centers on:
    • Support and consulting.
    • Avalonia XPF, a commercial WPF‑compatible platform, reportedly several thousand to ~20k USD per app per platform.

Migration & Target Scenarios

  • Strong appeal for:
    • Porting WPF apps to cross‑platform desktop (Windows/macOS/Linux/Web) with minimal changes, especially via XPF.
    • New desktop‑focused apps where consistent non‑native look is acceptable or desired.
  • Caveats:
    • Fewer drop‑in controls compared to WinForms/WPF ecosystems.
    • Porting Xamarin.Forms to Avalonia is seen as easier than to Flutter/React Native, but still significant work.
    • WinForms and .NET Framework → .NET Core/“dotnet” migration can be painful regardless of UI choice.

Languages & Alternatives

  • Best fit for teams already invested in .NET/C#/XAML.
  • F# support exists via community projects (FuncUI, Fabulous), but is considered less first‑class.
  • Compared against Flutter (more mature on mobile), Uno (more native‑control‑oriented), and other GUI/embedded engines.