FreeCAD is an Open Source parametric 3D CAD modeler. Parametric modeling allows you to easily modify your design by going back into your model history and changing its parameters. FreeCAD is open source (LGPL license) and completely modular, allowing for very advanced extension and customization.

LibreCAD is a free Open Source CAD application for Windows, Apple and Linux. Support and documentation is free from our large, dedicated community of users, contributors and developers. You, too, can also get involved!

BRL-CAD | Open Source Solid Modeling. A powerful cross-platform open source solid modeling system that includes interactive geometry editing, high-performance ray-tracing for rendering and geometric analysis, image and signal-processing tools, a system performance analysis benchmark suite, libraries for robust geometric representation, with more than 20 years of active development.

QCAD - 2D CAD for Windows, Linux & Mac. A free, open source 2D CAD system for Windows, Linux and Mac.

OpenSCAD is software for creating solid 3D CAD objects.
It is free software and available for Linux/UNIX, MS Windows and Mac OS X.

Archimedes is a free and open source CAD (Computer Aided Design) software. It is a robust system built over Eclipse's Rich Client Platform fully based on plug ins. This means it is easily extensible but also has a pretty thin core that allows you to select the features you need and drop the other ones easily.

SOLVESPACE is a free (GPLv3) parametric 3d CAD tool.

Applications include:

• modeling 3d parts — draw with extrudes, revolves, and Boolean (union / difference) operations
• modeling 2d parts — draw the part as a single section, and export DXF, PDF, SVG; use 3d assembly to verify fit
• 3d-printed parts — export the STL or other triangle mesh expected by most 3d printers preparing CAM data — export 2d vector art for a waterjet machine or laser cutter; or generate STEP or STL, for import into third-party CAM software for machining
• mechanism design — use the constraint solver to simulate planar or spatial linkages, with pin, ball, or slide joints
• plane and solid geometry — replace hand-solved trigonometry and spreadsheets with a live dimensioned drawing

2d/3d code based parametric CAD in Javascript.
Contribute to jscad/OpenJSCAD.org development by creating an account on GitHub.

Home of the Blender project - Free and Open 3D Creation Software

A complete 3D modeling tool. The geometric, topological and visualization algorithms of openCascade allow the creation 3D models for any discipline; for visualization or manufacturing. Modeling to visualisation - everything is possible.