Viewer 45
File Manager / General Viewer / Commandline utility / Generic Frontend
...It's fully functional however it would need some code Refinements, in addition to replacing the *.dwg support library to any open source one (libredwg or libdwg). Additional "C" or "C++" open source libraries could be added to support many formats as needed.
Complete source is supplied via GitHub
[ GNU GENERAL PUBLIC LICENSE Version 3, 29 June 2007 ]