The team behind Uno Platform released version 6.3 of the cross‑platform .NET UI framework, aimed at developers targeting mobile, desktop and WebAssembly using C# and XAML. The update includes early support for .NET 10 (RC1), compatibility with Visual Studio 2026’s new .slnx format, enhanced WebAssembly image‐decoding performance and refinements to the TabView control and the Hot Design visual editor.
Uno platform is an alternative UI platform for building multi-device applications in C# and XAML. It was launched in 2018, after years of internal use by a Canadian company nventive. It allows developers to write applications for Windows, iOS, Android, WebAssembly, macOS and Linux. It is released under the Apache 2.0 open-source license on GitHub.
Before version 6.3, the platform supported .NET 9 as the latest stable target. With Microsoft introducing changes to tooling and solution file formats, the latest release extends Uno Platform’s compatibility with upcoming development environments and runtime versions. Uno Platform 6.3 introduces new project templates that target .NET 10 RC1. While it allows testing against .NET 10 (and its experimental Android CoreCLR), the documentation confirms that .NET 9 remains the recommended stable target for production deployments.
The release also adds support for Visual Studio 2026’s new solution format, .slnx. Developers can open existing Uno projects in VS 2026 while maintaining compatibility with VS 2022. The associated Uno Platform Visual Studio extension has been updated to support both environments. This enables teams to evaluate the new IDE while retaining existing workflows in supported versions.
In WebAssembly targets, Uno Platform 6.3 modifies the way image decoding is handled. The framework now offloads image decoding to WebWorkers instead of the UI thread. This change allows decoding to run in parallel, improving responsiveness for scenarios involving large or numerous images, such as dashboards or media applications.
The TabView control has received additional configuration options. New sizing modes are available, including equal-sizing, compact, and size-to-content. Tabs can now be marked as non-closable, and runtime tab reordering is supported. These features apply across all supported platforms.
The Hot Design visual editor has been updated with a searchable control tree and enhanced property inspection capabilities. Controls like SplitView and NavigationView can now be configured through a visual interface. These changes affect only the design-time tooling and do not impact runtime behaviour.
Version 6.3 discontinues support for .NET 8 because of the .NET MAUI 8 mobile workloads being unsupported since March 2025. Developers targeting that runtime must upgrade to either .NET 9 or .NET 10 RC1.
Uno Platform’s announcement received limited direct feedback on social media. On Reddit, a related discussion referenced Uno in a broader context of .NET UI frameworks:
Like everybody is saying, it works like Avalonia. AFAIK it does cross-platform with a WinUI API paradigm. Neither has left the MS UI conceptual universe of XAML, WinUI, MVVM, etc. Neither have truly learned from SwiftUI, Flutter or Jetpack Compose.
The full release notes, migration instructions, and updated documentation are available on the Uno Platform blog.
