Open CASCADE Technology is software development platform freely available in open source. It includes components for 3D surface and solid modeling, visualization, data exchange and rapid application development.
The ObjectARX® programming environment provides object-oriented C++, C# and VB .NET application programming interfaces for developers to use, customize, and extend AutoCAD® software and AutoCAD-based products like AutoCAD® Architecture, AutoCAD® Mechanical, and AutoCAD® Land Desktop software.