Building MiKTeX

MiKTeX can be built on Windows. A subset of MiKTeX, called MiKTeX Tools, can be built on GNU/Linux:

Getting MiKTeX Source Code

You can download MiKTeX source code here:

MiKTeX 2.9-2015-08-27 Source Code
Version 2.9-2015-08-27, all platforms
Size: 20.67 MB