FreeCAD - An open-source parametric 3D modeler
Procore - Procore is the world's most widely used construction project management software. Easy to use, mobile platform with unlimited user licenses.
SketchUp - 3D for Everyone
BuilderTREND - Buildertrend is the #1 construction management software and construction app for home builders, remodelers, specialty contractors and commercial construction.
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
CoConstruct - CoConstruct's project management software helps custom builders & remodelers coordinate projects, communicate with clients & crew, and control.