In a significant move for cross-platform development, Microsoft has donated its Mono Project to WineHQ, as announced on August 27. The Mono Project, which has been essential in providing a .NET implementation on various platforms such as Android, iOS, and Linux, will now be managed by WineHQ, a nonprofit organization known for its compatibility layer that allows Windows applications to run on POSIX-compliant platforms like Linux, macOS, and BSD. The transition means that WineHQ will now take on the role of stewarding the Mono Project, with its source code available on GitLab under the WineHQ umbrella.
The Mono Project, which was launched in 2001, played a pioneering role in making the .NET platform cross-platform, allowing it to run on multiple operating systems beyond Windows. According to Jeff Schwartz from Microsoft, the project was instrumental in expanding .NET’s reach and making it a viable option for developers targeting platforms such as Linux, macOS, and mobile devices. The project helped establish a strong foundation for .NET to flourish in environments outside of Microsoft’s own ecosystem. Today, .NET is a versatile platform, supporting development for a wide range of devices and operating systems.
The last major update to Mono was in 2019, with a final patch released in February 2024. After Microsoft’s acquisition of Xamarin in 2016, the company became the steward of the Mono Project, helping to drive its development. However, with the transition of the project to WineHQ, Microsoft’s focus has shifted to a modern fork of the Mono runtime, which resides in the dotnet.runtime repository. This new fork represents the evolution of the Mono runtime, and its ongoing development has led to the gradual migration of workloads to this more contemporary solution.
With the future of Mono now under WineHQ’s care, Microsoft has recommended that current Mono users and maintainers of Mono-based frameworks consider migrating to .NET, which has absorbed much of the work from the Mono fork. Although existing Mono repositories and source code will remain available, they may eventually be archived, and binaries will be supported for up to four years. This shift marks a significant change in the .NET ecosystem and encourages developers to embrace the more modern .NET platform for future development.