SagCAD!

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. »

AutoCAD is a software application for both 2D and 3D computer-aided design (CAD) and drafting — available since 1982 as a desktop application and since 2010 as a mobile web- and cloud-based app, currently marketed as Autocad 360.

LibreCAD (originally QCad then CADuntu) is an open source 2D CAD application for Windows, Apple and Linux. It is based on Qt, which is a leading cross-platform application and UI development framework.

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.

A powerful CAD platform, with features familiar to you from native .dwg applications. BricsCAD® unifies advanced 2D design with the intelligence of 3D direct modeling. For Windows, Linux, and Mac.

NaroCAD is a fully fledged and extensible 3D parametric modeling CAD application.The goal of this project is to develop a fully fledged and extensible 3D CAD software based on the concept of parametric modeling of solids, comparable to well known solutions.These functionalities are interrelated through Model Associativity and are exposed through a GUI. The general usability specifications like saving, importing are described in General functionality specifications . The software can be extended through Plugins and programming interface. »

QCAD is an application for computer aided drafting in 2D. With QCAD you can create technical drawings such as plans for buildings, interiors, mechanical parts or schemas and diagrams. QCad uses the AutoCAD DXF file format internally and to save and import files. AutoCAD DWG support is available as a commercial plugin.

MEDUSA4: The comprehensive 2D/3D design automation suite for mechanical, plant, construction and automotive engineering

gCAD3D is a 3D CAD CAM application that features an integrated 3D OpenGL viewer, a program interpreter for geometry and NC-commands in 3D, an integrated NC-processor, and a programming interface for user programs. It has support for importing Step files and support for both importing and exporting Iges, DXF, and VRML files.

Industrial strength, user-friendly 2D/3D CAD package.Specialised Toolkits to enhance your productivity.Control Centre allows easy access to symbols, hatching, text, dimension and line styles.Enhanced bitmap capability can load 300 large images.Full compatibility with the latest DWG/DXF formats.On-going Development and unbeatable local support.

KediCAD - CAD(Computer Aided Design) -  CAM(Computer aided Manufacturing) - FEA(Finite Element Analysis)  software for Linux. It has 2 version.    1-) KediCAD2B (2 dimesional version)    2-) KediCAD3B (3 dimensional version) .

Three versions of devCad are available: devCad LE | devCad Pro | devCad Cam Pro.

NttCAD: free, simple 2D/3D CAD software, multi-platform (works on Windows, Mac, linux...). Programmable in Java language. Small program size and fast download. Saves in autocad dxf, svg and NttCAD formats.

2-D engineering drawing editor that supports hierarchical object description. It is inspired by Hewlett-Packard's proprietary HP PIGLET (Personal Interactive Graphic Layout EdiTor), which later became the commercial Graffy editor by DURST CAD.