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FreeCAD is a general purpose parametric 3D CAD modeler. The development is completely Open Source (LGPL License). FreeCAD is aimed directly at mechanical engineering and product design but also fits in a wider range of uses around engineering, such as architecture or other engineering specialties.FreeCAD features tools similar to Catia, SolidWorks or Solid Edge, and therefore also falls into the category of MCAD, PLM, CAx and CAE. It is a feature based parametric modeler with a modular software architecture which makes it easy to provide additional functionality without modifying the core system.As with many modern 3D CAD modelers it has many 2D components in order to sketch 2D shapes or extract design details from the 3D model to create 2D production drawings, but direct 2D drawing (like AutoCAD LT) is not the focus, neither are animation or organic shapes (like Maya, 3ds Max, Blender or Cinema 4D), although, thanks to its wide adaptability, FreeCAD might become useful in a much broader area than its current focus.FreeCAD makes heavy use of all the great open-source libraries that exist out there in the field of Scientific Computing. Among them are OpenCascade, a powerful CAD kernel, Coin3D, an incarnation of Open Inventor, Qt, the world-famous UI framework, and Python, one of the best scripting languages available. FreeCAD itself can also be used as a library by other programs.FreeCAD is also fully multi-platform, and currently runs flawlessly on Windows and Linux/Unix and Mac OSX systems, with the exact same look and functionality on all platforms. »

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

BRL-CAD is 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.

SolveSpace is an Open Source 2D and 3D CAD (computer-aided design) program. It is a constraint-based parametric modeler with simple mechanical simulation capabilities. It is developed by Jonathan Westhues.

Browser based 3D solid CAD editor, Openscad style, with a Coffeescript based syntax, using only Coffeescript + Javascript

Antimony is a computer-aided design (CAD) tool from a parallel universe in which CAD software evolved from Lisp machines rather than drafting tables.

CadQuery is an intuitive, easy-to-use python based language for building parametric 3D CAD models. CadQuery is for 3D CAD what jQuery is for javascript. Imagine selecting Faces of a 3d object the same way you select DOM objects with JQuery!

ImplicitCAD is a programmatic CAD program, implemented in Haskell. Unlike traditional CAD programs, programmatic CAD programs use text descriptions of objects, as in programming. Concepts like variables, control structures and abstraction are used, just as in programming. This provides a number of advantages:

ScratchyCAD is a web-based parametric 3D design software with a block-based programming language to create objects for 3D printing, animations, games and websites.