Asp.net is fully open source technology.available on preview vs14 for exploration.
You can explore as asp.net Vnext is future of .net
Yo explore you require vs 14 ctp (community techanical preview) version .
Some useful things in it:-
》 configuration file are moved to json format from xml format.
》project reference dependencies files are json file like node.js techanology
》 you can use any platform window , mac or linux as it is available with mono project.
》 you can modify c# file directly without stopping run and hit enter on browser to see result. As compiler a redesigned by microsoft.
》No web form will be in this technology.
》.net framework is asp.net framework 5