The standard graphical subsystem for UNIX and Linux, called X, has its own libraries for GUI development. They provide a low-level programming interface to X, but tend to be hard to use. Old end-user applications and other toolkits of course make good use of them. Nowadays the Linux GUI scene is dominated by GTK+ and Qt, since two popular, complete user environments - GNOME and KDE - are based on them.
Common name or abbreviation of the toolkit.
Whether the toolkit is suitable for a newbie programmer.
Different licenses for different GUI toolkits have practical significance. GTK+, TK and GNUstep licenses allow you to develop both open source and closed source applications without paying for a license. Motif license requires payment, while the QT license requires payment only if you write closed source programs.
The language that is most often used with the toolkit.
Other languages which can use the toolkit.
Applications that use the toolkit.
Additional information on the toolkit.
| Library | Beginner | License | Language | Bindings | Examples | Comments |
| TK | Yes | Free | TCL | Perl, Python, others | make xconfig, TKDesk | |
| GTK+ | No | Free (LGPL) | C | Perl, C++, Python, many others | GNOME, Gimp | Very popular |
| QT | No | Free for open source | C++ | Python, Perl, C, others? | KDE | Very popular |
| Motif | No | Non-free | C/C++ | Python, others? | Netscape, Wordperfect | Lesstif isa free replacement |
| GNUstep | No | Free (LGPL) | Objective C | Guile, Java? | None widely known, but see the application list | GNUstep is still under development |