Microsoft open sources its most popular Windows UX frameworks and says the first preview of .NET Core 3.0 is now available
Microsoft is open sourcing WPF, Windows Forms and Win UI via GitHub and making available the first public preview of Visual Studio 2019.
Context & Ripple Effects
This closes a loop Microsoft started years ago: after .NET Core reached version 1.0 with Linux and OS X support in 2016 and .NET Core 2.0 hit general availability in 2017, the runtime was open but the Windows desktop UI layer — WPF, Windows Forms, WinUI — stayed closed. Open sourcing those frameworks on GitHub extends the open-source model from the runtime up into the client stack itself.
The timing matters because it lands alongside the first public preview of Visual Studio 2019 and the first .NET Core 3.0 preview, positioning the next tooling cycle around an open desktop framework rather than a proprietary one. It also echoes earlier attempts like the open-source Windows Bridge for porting iOS apps, part of the same campaign to keep developers building for Windows.
First-order effects
- Developers maintaining legacy WPF and Windows Forms applications can now read, file issues against, and contribute to the frameworks on GitHub instead of waiting on Microsoft's release cadence.
- Teams can begin testing their existing Windows desktop code against the first .NET Core 3.0 preview, which is the vehicle that carries these frameworks onto the modern .NET Core runtime.
Second-order effects
- Third-party UI component vendors and tooling builders whose products wrap WPF and Windows Forms gain a public roadmap to plan against, while cross-platform desktop stacks lose one of their strongest arguments — that Microsoft's desktop frameworks were closed and Windows-only-bound at the framework level.
- The Visual Studio 2019 preview gives the open frameworks a shipping IDE on day one, pulling enterprise desktop developers into testing both together rather than adopting them separately.
Third-order effects
- If the pattern holds — runtime in 2016, tooling previews now, UI frameworks today — Microsoft's Windows client development story converges fully with its open-source .NET strategy, lowering the switching cost that historically pushed desktop developers toward web or cross-platform alternatives.
- Community contributions to WPF and Windows Forms could shift maintenance of decades-old enterprise UI code from a purely internal Microsoft burden toward a shared model, though how much external contribution the frameworks actually attract remains genuinely uncertain.
The trend: Microsoft is steadily moving its entire developer stack — runtime, tooling, and now the Windows desktop UI frameworks themselves — from proprietary to open source, one layer per release cycle.