Aims to create a consistent graphical user interface experience for free and Open Source software. Style guidelines, basic icon library, and list of projects using tango icons.

The standard window manager for Linux, stable but not as pretty as Window Maker or Enlightenment.

A free, multiple platform C++ graphical user interface framework.

An open source cross-platform C++ based Toolkit for GUI development.

Open source widget server. (Python, Ruby, GTK2) [OS Independent]

C++ framework created to provide platform GUI framework, features such as Java and Java's Swing, and Borland's Visual Component Library.

Toolkit for multi-platform GUI development. (Perl) [OS Independent]

An engine that reads XML files describing graphical user interfaces layout.

A GUI being developed for older DOS systems that are incapable of running Windows.

Open source GUI for less powerful or old computers.