By Paul Thurrott
Publication Date: 2026-08-29 16:02:00
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…