Can you develop Linux applications with Xamarin?

No, Xamarin is not available for Linux. This was a conscious decision made by the Xamarin team several years ago:

Miguel de Icaza 2011-08-04 11:52:37 UTC

We face a QA problem here.

The problem with supporting Linux is that we would need to create a self-contained Mono packaging for all of the bits we ship since most Linux distributions are slightly off when it comes to Mono.

It also means that if we advertise "Linux" we would need to QA a dozen different combination due to different Linux distributions and different editions of each distribution.

Perhaps we would support just a single distribution and a single version, which is closer to what we have to do on Windows/Mac today.

To clarify, the Xamarin product range is not available on Linux (Xamarin Studio, Xamarin.iOS and Xamarin.Android) but MonoDevelop, the foundation of Xamarin Studio, and Mono, the cross-platform .NET runtime, definitely is.

You can build desktop software using MonoDevelop. The MonoDevelop site has plenty of instructions on getting started:

• Install MonoDevelop on Linux

Just in case someone else comes accross this q/a: the situation has changed. With Xamarin.Forms 3.0, Gtk# is supported (as preview, at this moment). Therefore, full Linux GUI support is enabled.

So, Xamarin now covers:

• Android
• iOS
• UWP apps
• WPF apps
• Linux Gtk desktop applications
• Mac OS
• Watch OS
• tv OS
• Tizen

The only thing left to wish for: JS/HTML5 Web App target platform, as part of Xamarin :)

Seems that there is a chance of Xamarin Forms work on linux distros. In this reddit thread Miguel de Icaza says:

Some of our team members actually develop in Linux. The reason why we never released the Linux tools is because we were charging a lot of money and people would rightfully expect the software to be fully supported. We had enough keeping our Mac and Windows users happy, and adding an unknown number of Linux distributions sounded like a hard task. Now that we are open sourcing the SDKs and I no longer will feel bad if something does not work under a particular Linux configuration, I will be happy to release the Linux builds.

That is: the fact that Forms is an open source tool currently opens this possibility.