CAD - Computer Aided Design

FreeCAD

FreeCAD is made primarily to design objects for the real world.
https://www.freecad.org/
Downloads:
https://www.freecad.org/downloads.php

LibreCAD

LibreCAD is a free Open Source 2D-CAD application for Windows, Apple and Linux.
https://librecad.org/
Downloads:
https://librecad.org/#download

Sweet Home 3D

Sweet Home 3D is aimed at people who want to quickly design the interior of their home.
https://sweethome3d.com/
Download:
https://sweethome3d.com/download.jsp