Microsoft Offloads The Mono Project To Wine

Coming as a surprise this afternoon is Microsoft deciding to contribute the Mono Project to be stewarded by the Wine development community.

It's been five years since the last major Mono Project release as an open-source .NET framework. Microsoft has decided to let WineHQ now oversee the upstream Mono Project. Wine already makes use of Mono and this move makes sense with Microsoft focusing on open-source .NET and other efforts. Formally handing over control of the upstream Mono project to WineHQ is a nice move by Microsoft rather than just letting the upstream Mono die off or otherwise forked.

Microsoft posted to the Mono-Project.com project site:

The Mono Project (mono/mono) (‘original mono’) has been an important part of the .NET ecosystem since it was launched in 2001. Microsoft became the steward of the Mono Project when it acquired Xamarin in 2016.

The last major release of the Mono Project was in July 2019, with minor patch releases since that time. The last patch release was February 2024.

We are happy to announce that the WineHQ organization will be taking over as the stewards of the Mono Project upstream at wine-mono / Mono · GitLab (winehq.org). Source code in existing mono/mono and other repos will remain available, although repos may be archived. Binaries will remain available for up to four years.

Microsoft maintains a modern fork of Mono runtime in the dotnet/runtime repo and has been progressively moving workloads to that fork. That work is now complete, and we recommend that active Mono users and maintainers of Mono-based app frameworks migrate to .NET which includes work from this fork.

We want to recognize that the Mono Project was the first .NET implementation on Android, iOS, Linux, and other operating systems. The Mono Project was a trailblazer for the .NET platform across many operating systems. 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.

Thank you to all the Mono developers!

Microsoft acquired Xamarin back in 2016 as the developers behind Mono and other Xamarin projects. Mono originally was started by Miguel de Icaza and the gang as Ximian that was acquired by Novell two decades ago and then SUSE handed off Mono control to Xamarin in 2011.