Microsoft has completed the open-source migration of WinUI, Windows 11’s native user interface framework, moving its mainline development to GitHub for public development and review.
Microsoft has completed the planned open-source migration of WinUI, the native user interface framework used for Windows 11 applications. Mainline development is now taking place publicly on GitHub, where branches, pull requests and code reviews can be tracked openly.
The move marks the completion of a multi-stage effort that Microsoft began after announcing plans to open-source WinUI more than a year ago. The company followed a four-phase migration process, with the third phase completed in May 2026 and the final stage now bringing mainline development into the public repository.
For now, pull requests are primarily being submitted by Microsoft developers as the company tests its end-to-end development processes. This is intended to establish a stable workflow before the project begins accepting contributions from the wider developer community.
Making WinUI development public gives developers greater visibility into the evolution of the framework and allows them to follow changes affecting Windows application development. WinUI is used for building native Windows applications and remains an important part of Microsoft’s Windows App SDK ecosystem.
Microsoft has indicated that completing the migration does not mark the end of its broader open-source plans for WinUI. Additional milestones are expected to be announced publicly, including plans to eventually open the project to community pull requests, further expanding external participation in the development of Windows’ native UI framework.
