Microsoft announces Project Reunion to unify Win32 and UWP APIs on Windows

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Microsoft Windows 10X

Project Reunion Windows 10x

At Build 2020, Microsoft today announced Project Reunion, a new project to make app development easier for Windows 10 platform. Project Reunion unifies access to existing Win32 (legacy Windows API) and UWP (Universal Windows Platform) APIs and make them available decoupled from the OS, via tools like NuGet. Apps built using Project Reunion components can work across all the Windows 10 versions and devices.

This will provide a common platform for new apps. Plus, it will help developers update and modernize your existing apps with the latest functionality, whether they’re C++, .NET (including WPF, Windows Forms, and UWP) or React Native.

One of the first components in the Project Reunion is WinUI 3 Preview 1 which is a modern UI platform that allows developers to improve their C++, WPF, and Windows Forms incrementally.

WebView2 is an another component in the Project Reunion that allows developers to embed a Chromium-based WebView in Windows Forms, WPF, and UWP/ WinUI 3 app. Developers can also get full web functionality without being locked into a single version of Windows. WebView2 will be decoupled from the OS.

Project Reunion principles:


Project Reunion works in all your apps – Win32, Packaged, and UWP – and across many versions of Windows.


Project Reunion supports your app’s use of modern software libraries for UI, AI, ML, packaging, frameworks, and libraries. Language projections for C++, Rust, C#, and JavaScript expand the benefits to all your apps. Cloud-backed apps, streaming, and edge-compute apps are all great places to use Project Reunion’s capabilities.


Project Reunion ships out of band with OS releases, with regular previews. You get to incrementally adopt Project Reunion components for your existing apps and middleware libraries using NuGet.


We’re committing to engineering Project Reunion in the open on GitHub, so you have a more direct say in how the platform evolves and can even help out.

You can learn more about Project Reunion here.

More about the topics: developers, microsoft, Project Reunion, UWP, Win32, windows 10