A long, weird FOSS circle ends as Microsoft donates Mono to Wine project

Microsoft has donated the Mono Project, an open-source framework that brought its .NET platform to non-Windows systems, to the Wine community. WineHQ will be the steward of the Mono Project upstream code, while Microsoft will encourage Mono-based apps to migrate to its open source .NET framework.

As Microsoft notes on the Mono Project homepage, the last major release of Mono was in July 2019. Mono was “a trailblazer for the .NET platform across many operating systems” and was the first implementation of .NET on Android, iOS, Linux, and other operating systems.

Ximian, Novell, SUSE, Xamarin, Microsoft—now Wine

Mono began as a project of Miguel de Icaza, co-creator of the GNOME desktop. De Icaza led Ximian (originally Helix Code), aiming to bring Microsoft’s then-new .NET platform to Unix-like platforms. Ximian was acquired by Novell in 2003.

Mono was key to de Icaza’s efforts to get Microsoft’s Silverlight, a browser plug-in for “interactive rich media applications” (i.e., a Flash competitor), onto Linux systems. Novell pushed Mono as a way to develop iOS apps with C# and other .NET languages. Microsoft applied its “Community Promise” to its .NET standards in 2009, confirming its willingness to let Mono flourish outside its specific control.

By 2011, however, Novell, on its way to being acquired into obsolescence, was not doing much with Mono, and de Icaza started Xamarin to push Mono for Android. Novell (through its SUSE subsidiary) and Xamarin reached an agreement in which Xamarin would take over the IP and customers, using Mono inside Novell/SUSE.

Microsoft open-sourced most of .NET in 2014, then took it further, acquiring Xamarin entirely in 2016, putting Mono under an MIT license, and bundling Xamarin offerings into various open source projects. Mono now exists as a repository that may someday be archived, though Microsoft promises to keep binaries around for at least four years. Those who want to keep using Mono are directed to Microsoft’s “modern fork” of the project inside .NET.

What does this mean for Mono and Wine? Not much at first. Wine, a compatibility layer for Windows apps on POSIX-compliant systems, has already made use of Mono code in fixes and has its own Mono engine. By donating Mono to Wine, Microsoft has, at a minimum, erased the last bit of concern anyone might have had about the company’s control of the project. It’s a very different, open-source-conversant Microsoft making this move, of course, but regardless, it’s a good gesture.