DraftSight is a proprietary freeware 2D computer-aided design (CAD) software application developed by Dassault Systèmes. It lets users create, edit and view .dwg and AutoCAD DXF files. Dassault are better known for their 3D CAD software that is widely used in the Aerospace industry and elsewhere.

http://www.3ds.com/products-services/draftsight/overview/
http://en.wikipedia.org/wiki/DraftSight