Floorplanner - Floor plan interior design software. Design your house, home, room, apartment, kitchen, bathroom, bedroom, office or classroom online for free or sell real estate better with interactive 2D and 3D floorplans.
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
Sweet Home 3D - Sweet Home 3D is a free interior design application that helps to draw the plan of house, arrange furniture on it and visit the results in 3D.
NttCAD - Free 2D/3D CAD software, easy to use and multi-platform
SketchUp - 3D for Everyone
QCAD - QCAD is an application for computer aided drafting in 2D.