Mono is basically the .NET Framework on FreeBSD or other open source platforms. This allows development in C# on FreeBSD.  C# is an extremely popular language that is not slowing down.  It’s popularity stems from that fact that this language and its features allow for much rapid development than many other languages.

The version of Mono available in the ports tree is not the latest version available. Just like FreeBSD has a release version and a development version, Mono has a release version and a development version.  The development version is so much newer that it is hard not to recommend it over the release version.

Step 1 – Install the latest ports

This is already documented here:

How to install ports on FreeBSD?

Step 2 – Install portshaker

The team at BSD# have a tool called portshaker that adds mono ports to the ports tree.  Install it as follows.

Step 3 – Configure portshaker

The example portshaker.conf.example is configured correctly for default configurations, so all we need to do is copy it.

Step 4 – Run portshaker

Yes, it is that easy.  Simply run portshaker.

Note: You may be prompted to merge a few files. I chose install each time.

Your ports tree is now updated by portshaker.

Step 5 – Install mono

The mono port should now be updated to the latest version.

Mono is now installed on your system.

There is an example of building a hello world app here:

C# (Mono) on FreeBSD