Follow this list for the appropriate Visual Studio version and edition.

For version 2.3 or newer

Visual Studio Community Edition 2015 (freeware) or Visual Studio Express Edition (freeware) with NET 4.6.1 DEV pack

For version 2.2

To be able to compile the version 2.2. add-ins, download and install the Visual Studio Express 2013 (freeware) and the .NET Framework 4.5.2 multi-targetting pack (382Mb). Visual Studio Express 2013 will prompt you on the first access to download it. The link is https://www.microsoft.com/en-us/download/details.aspx?id=42637.

For builds 2081 or newer:

Visual Studio Express 2013 (freeware)

For builds 1386 or newer:

Visual Studio Express 2012 (freeware)

For builds 1180 till 1385:

Visual Studio Express 2010 (freeware)