Autodesk DWG TrueView - Get a free DWG viewer to view, open, edit, and convert .dwg files, the native file format for AutoCAD files. DWG Trueview includes DWG TrueConvert.
progeCAD - progeCAD is DWG/DXF-native CAD software, built for professional drafting.
Autodesk Design Review - Design Review lets you view, mark up, print, and track changes to 2D and 3D files.
BricsCAD - A powerful CAD platform, with features familiar to you from native .dwg applications.
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.
MicroSurvey Software - MicroSurvey CAD is a full-featured CAD package that lets you do everything from creating point clouds to designing complex survey networks.