SketchUp - 3D for Everyone
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
FreeCAD - An open-source parametric 3D modeler
DraftSight - Discover Dassault Systèmes®' DRAFTSIGHT™ Professional CAD software that lets you create, edit, view and markup any kind of 2D drawing. Learn more here.
nanoCAD - nanoCAD is a pro-grade 2D CAD system with native DWG support and full customizability.
BricsCAD - A powerful CAD platform, with features familiar to you from native .dwg applications.