FreeCAD - An open-source parametric 3D modeler
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
SolidWorks - Dassault Systèmes SolidWorks Corp. develops and markets 3D CAD design software, analysis software, and product data management software. SolidWorks is the leading supplier of 3D CAD product design engineering software.
SketchUp - 3D for Everyone
QCAD - QCAD is an application for computer aided drafting in 2D.
Autodesk AutoCAD - Autodesk AutoCAD is a commercial computer-aided design (CAD) and drafting software application.