Microsoft announces open source Windows Forms and WPF

On 04/12/2018, during the Microsoft Connect(); 2018 conference, Microsoft announced that it was open-sourcing three major Windows user interface frameworks: Windows Presentation Foundation, Windows Forms, and the Windows UI XAML Library. The company released the frameworks on GitHub under the MIT License, allowing developers to view source code, contribute changes, and report issues directly. The move was presented as part of Microsoft’s broader shift toward open development and community collaboration. The announcement coincided with the first preview of .NET Core 3.0, which added support for WPF and Windows Forms on the modern .NET Core runtime. Microsoft said this integration would allow developers to build desktop applications using improved performance, side-by-side deployments, and modern tooling while maintaining compatibility with existing Windows applications. The Windows UI XAML Library was also made available as open source to support future interface development aligned with Windows design systems. Microsoft stated that the frameworks would remain Windows-only despite being open source because they depend on Windows-specific technologies such as DirectX and GDI+. The company emphasized that open-sourcing the UI stack would provide transparency between Microsoft engineers and developers, enabling community contributions, bug fixes, and improved debugging capabilities.