Crystal Space is an unmaintained[2] framework for developing 3D applications written in C++ by Jorrit Tyberghein and others.

It is very portable and runs on Microsoft Windows, Linux, UNIX, and Mac OS X.

It is also free and open-source software, licensed under the GNU LGPL-2.0-or-later, and was SourceForge.net's Project of the Month for February 2003.

The client programs use the plugins, such as the OpenGL 3D renderer, by registering them via Crystal Space's Shared Class Facility (SCF).

Crystal Space has modules for 2D and 3D graphics, sound, collision detection and physics through ODE and Bullet.