SketchUp - 3D for Everyone
nanoCAD - nanoCAD is a pro-grade 2D CAD system with native DWG support and full customizability.
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
DraftSight - Discover Dassault Systèmes®' DRAFTSIGHT™ Professional CAD software that lets you create, edit, view and markup any kind of 2D drawing. Learn more here.
Autodesk AutoCAD - Autodesk AutoCAD is a commercial computer-aided design (CAD) and drafting software application.
FreeCAD - An open-source parametric 3D modeler