Geometry Handling Library

A library for 2-D and 3-D geometric calculation in C, with functions for shape generation, geometric evaluation, intersection, and offsetting and filleting.
http://www.pml.co.jp/ghl/index.html

CurveTrainer

A basic experimental lab for geometric shape processing, for learning about the mathematical theory and practical maipulation of vairous parametric curves
http://www.pml.co.jp/cvt/index.html

VectorDraw Drawing Components

Object oriented 2D/3D graphics libraries with AutoCAD file format support, as well as a web-based version.
http://www.vdraw.com/

DeveloCAD.com

Graphics libraries for Delphi developers, such as an OpenGL canvas, hidden lines algorithms, and geometry data management.
http://www.develocad.com/

Geometric Software Solutions

Technology provider to CAD/CAM/CAE vendors, offering components for geometry manipulation, information management, and collaborative engineering.
http://www.geometricsoftware.com/

Cadmai Software GmbH

Cadmai ist a parametric and relational CAD module that can be integrated as a intelligent viewer in other applications.
http://www.cadmai.com/

Open CASCADE

A 3D modeling kernel that consists of reusable C++ object libraries that are available as Open Source.
http://www.opencascade.com/

C4W

Offers modelling kernel libraries and related tools for construction, analysis, and presentation of 3D models.
http://www.c4w.com/

D-Cubed

Supplies geometric constraint managers, hidden line and collision detection components to the CAD/CAM industry.
http://www.d-cubed.co.uk/index.htm

Spatial Technologies, Inc.

Develops, markets and supports software components for 3D modeling, visualization, and interoperability, such as the ACIS solid modelling kernel.
http://www.spatial.com/

Gardos Software

Avax ActiveX control to view, create, edit, print, and manage 2D vector drawings.
http://business.hol.gr/gardos/

KolbaSoft

The VeCAD 2D vector graphics library can be used to create CAD applications.
http://www.kolba.com/

SCS Mothership, Ltd.

Offers technology to display and manipulate 3D CAD and terrain models, designed to be embedded into GIS, CAD, technical documentation and e-learning applications.
http://www.scs-mothership.com/

Calligraphic Interface for Tridimensional Surface Modeling

An educational project trying to develop a gesture-based interface for 3D modeling. It uses wxWindows, ACIS, OpenGL and DevIL.
http://virtual.inesc.pt/~tfdc

Soft Gold, Ltd.

AutoCAD DXF tools for developers. ABViewer for Windows Commander and Far Manager. 3d DXF viewing and printing with C++, VB, and Delphi.
http://www.cadsofttools.com/

Weresc

Offers CADE, a CAD ActiveX control to view and edit 2D vector graphic, with web and DXF support.
http://www.weresc.com/

IntegrityWare, Inc.

Offers libraries for geometric solvers, trimmed surfaces, and polygon optimization, including visualization features.
http://www.integrityware.com/

Kotem Technologies Inc.

Offers components for CAD/CAM software, such as the 3D Core CAD-engine, the SmartFit 3D best-fitting application, and related functionality.
http://www.kotem.com/