Havenly - Havenly designs your room. We connect you with professional interior designers and help you get everything you need for a beautiful room, for one flat fee. No hassle, fun decorating.
FreeCAD - An open-source parametric 3D modeler
Decorist - Beautiful online interior design for a low flat fee.
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
SHAXPIR - A modern cloud workspace for fiction writing & worldbuilding
SketchUp - 3D for Everyone