Microsoft has donated its Mono Project, which has provided a .NET implementation on Android, iOS, Linux, and other operating systems, to the WineHQ organization, according to bulletin publicized August 27.
WineHQ provides a compatibility layer for running Windows applications on Posix-compliant platforms such as Linux, macOS, and BSD. The organization will take over as stewards of the Mono Project upstream at https://gitlab.winehq.org/wine-mono/mono.
Launched in 2001, the Mono Project was a trailblazer for the .NET Platform across many operating systems, Microsoft’s Jeff Schwartz wrote in an August 27 posting on GitHub. “It helped make cross-platform .NET a reality and enabled .NET in many new places and we appreciate the work of those who came before us,” Schwartz wrote. Today, .NET itself runs on Windows, macOS, and Linux, and can be used to build native applications for Windows, macOS, Linux, iOS, and Android.
The last major release of the Mono Project was in July 2019, while the last patch for the software was released in February 2024. Microsoft became the steward of the Mono Project when the company acquired Xamarin in 2016. Source code in existing mono/mono repos will remain available, although repos may be archived. Binaries will be available for as long as four years.
Microsoft, meanwhile, maintains a modern fork of the Mono runtime in the dotnet.runtime repo. Workloads have been progressively moving to that fork, and work on that is now complete. Stewards of Mono at Microsoft recommend that active Mono users and maintainers of Mono-based frameworks migrate to .NET, which includes work from this fork.