DWG FastView - DWG FastView for Windows is a lightweight dwg/dxf drawing viewer and editor produced by Gstarsoft, no need of dwg format conversion, vector graph magnified without distortion and full compatible with AutoCAD DWG/DXF.
A360 VIEWER - Free online CAD Viewer
DXF View - A lightning-fast drawing viewer enables you to view DXF and DWG™ files on Mac
STP Viewer - Free STP Viewer - free software that lets you view 3D STEP files (.stp, .step file format).
de·caff DXF Viewer - The DXF viewer is a Java program which displays DXF and SHX files
Glovius - Extensible & customizable 3D viewer, for consumption of product design data.