progeCAD - progeCAD is DWG/DXF-native CAD software, built for professional drafting.
FreeCAD - An open-source parametric 3D modeler
BricsCAD - A powerful CAD platform, with features familiar to you from native .dwg applications.
SketchUp - 3D for Everyone
MicroSurvey Software - MicroSurvey CAD is a full-featured CAD package that lets you do everything from creating point clouds to designing complex survey networks.
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.