EPiServer is a CMS, it’s not very well known outside of northern Europe – but here its use is quite extensive, especially in Sweden (since it originated out of our capital, Stockholm). I’ve been working full-time as an EPiServer developer for the better part of two years now, sure few side projects in Wordpress, Code Igniter or some other of the myriad of web platforms/frameworks that exist have been churned out also. But mostly in EPiServer, by far.