JetBrains has announced Project Rider, a cross-platform IDE for C# that runs on Windows, Mac and Linux, via a session at the NDC developer conference in London.

These are interesting times for Windows developers, with the PC in decline and Microsoft's mobile platform suffering from tiny market share. Cross-platform C# offers the possibility of porting code from Windows to other platforms such as iOS, Android and OS X, or developing for Microsoft's ASP.NET web framework using a Mac.

Microsoft itself is encouraging this approach, integrating Xamarin's C# compilers for iOS and Android into Visual Studio, and creating a cross-platform version of .NET called .NET Core.

The forthcoming ASP.NET 5 runs on .NET Core, which supports Windows, Linux or Mac (Mac support is intended for development only).

The fact that the Visual Studio IDE is Windows-only has become a problem. Microsoft has come up with a lightweight open source editor called Visual Studio Code, but the project is in its early stages and with limited features. Xamarin also has a cross-platform C# IDE, called Xamarin Studio, but that is geared towards its own mobile compilers.

Now JetBrains is aiming to fill the gap with Project Rider, a standalone C# IDE based on combining its existing ReSharper add-on for Visual Studio with the IntelliJ platform used for its other IDEs.

According to the company's Matt Ellis, "there's an ever-increasing tendency of developers using non-Windows platforms", adding that "Microsoft moving its platform and C# language towards open source have been an added incentive".

Project Rider will include familiar functionality from ReSharper, such as "Quick Fixes, Inspections and Smart Navigation". Refactoring support will be limited at first, awaiting additions to the user interface. A built in decompiler will display generated C# source code for types where source is not available.

Project Rider will support the Windows-only .NET Framework, the cross-platform Mono platform, and Microsoft's CoreCLR (also known as .NET Core), with build, run and debug features, though CoreCLR debugging is "in the works", said Ellis.

ReSharper will continue to be available for Visual Studio, and it looks as if JetBrains will share the ReSharper code across the two products. In Project Rider, ReSharper running on .NET or Mono runs in a separate process. The front end, written in the JVM language Kotlin, communicates with ReSharper via a custom API.

Price and licensing details have not yet been announced, though it will be in line with the company's move towards subscription licensing using its JetBrains Toolbox package.

A private preview is expected towards the end of February, with full release in Autumn 2016. ®