Dassault “DraftSight” Fully functional cad package! For Free!
https://www.3ds.com/products-services/draftsight-cad-software/free-download/
Bentley “View” you can print 3D PDF files! View Bentley objects.
https://www.bentley.com/en/products/product-line/modeling-and-visualization-software/bentley-view
AutoDesk “TrueView” standard viewer for AutoCAD.
http://www.autodesk.com/products/dwg/viewers
Dassault eDrawings
http://www.edrawingsviewer.com/
