Microsoft Moves WinUI/WASDK Development to GitHub

As part of a years-long effort to open up its Windows developer technologies, Microsoft has moved WinUI (formerly WinUI 3) and Windows App SDK (WASDK) development to GitHub.

“Mainline WinUI development is now taking place on GitHub,” a Microsoft engineer explains. “WinUI engineers and other Microsoft developers are creating branches, opening pull requests, reviewing, validating, and merging changes right here in this repository. Our day-to-day engineering work now happens in the open, so you can follow progress as it happens instead of waiting for changes to land.”

This is the fourth of four phases of a plan that Microsoft revealed in August 2025 when it said that it would address the many complaints developers have about these long-neglected technologies and make their maintenance and update more open and collaborative with the community. It has not open sourced WinUI and WASDK–which Microsoft now commingles as a single thing, called WinUI–but it is working toward that goal deliberately over time.

Microsoft provided an update on this work at Build 2026 back in May, as part of a broader push to address “pain points” in Windows 11. But with this milestone behind it, Microsoft is now developing WinUI in the open on GitHub, though only Microsoft employees can impact the codebase directly. After it proves that this development system is working, it will open up the GitHub repository for community contributions as well. Then it can push forward towards its ultimate goal making WinUI open source, as it did previously with legacy Windows developer frameworks like Windows Presentation Foundation, Windows Forms, and the Windows UI XAML Library.