| [Mesa](http://www.mesa3d.org/) | Mesa is an open-source implementation of the OpenGL specification - a system for rendering interactive 3D graphics. |
| [ParaView](http://www.paraview.org) | ParaView is a scientific parallel visualizer. |
| [pixman](http://www.pixman.org/) | Pixman is a low-level software library for pixel manipulation, providing features such as image compositing and trapezoid rasterization. Important users of pixman are the cairo graphics library and the X server. |
| [Tk](http://www.tcl.tk/) | Tk is an open source, cross-platform widget toolchain that provides a library of basic elements for building a graphical user interface (GUI) in many different programming languages. |
| [X11](https://www.x.org) | The X Window System (X11) is a windowing system for bitmap displays |