Microsoft is taking significant strides toward decoupling its Windows developer platform from the operating system itself with the release of the Project Reunion SDK 0.5. This marks the first major milestone in the project, introducing WinUI 3.0 UI controls and serving as a “first round of validating our work with customers prior to release,” according to Microsoft. It also marks a notable achievement, as developers can now publish MSIX-packaged desktop apps to the Windows Store, opening up new possibilities for app distribution on Windows.
While the 0.5 release only offers production support for a limited set of APIs and targets, Microsoft is encouraging developers to start porting their apps to this new platform. Project Reunion will not replace the existing Windows SDK, which will continue to evolve alongside Windows. Instead, it provides a unified access point to the Windows SDK and the Windows UI layer, simplifying the process of updating older applications to take advantage of modern Windows security features, hardware, and services.
One of the key advantages of Project Reunion is its flexibility in supporting a wide variety of development approaches. APIs will be accessible via WinRT for .NET applications and native C for C++/Win32. Currently, the available builds include support for C# with .NET 5 and C++ with WinRT. Microsoft is also looking to the future, offering a Rust/WinRT build for developers experimenting with the memory-safe Rust language. The company has made a significant investment in Rust, and this early support for Project Reunion will help developers quickly adopt modern development practices using this emerging language.
Project Reunion is hosted on GitHub, where developers can find installation instructions, documentation, and access to the source code. With this move, Microsoft is opening the doors for a more unified and streamlined development experience on Windows, helping developers modernize their applications while ensuring compatibility with the latest Windows features.