A Great free AutoCAD Drawing Viewer
AutoCAD
AutoCAD: The most popular tool you can use
GstarCAD (64-Bit)
More stable and faster, GstarCAD 2016 is an optimized CAD platform to save countless hours of design and rework
Inkscape
Inkscape - Create and edit graphic vectors with total simplicity
Illustration & graphic design
A Feature-Packed Yet Affordable Vector Design Tool