X Window programs

xterm is the standard terminal emulator for the X Window System. It allows users to run programs which require a command-line interface.

Xpdf is a free and open-source PDF viewer and toolkit based on the Qt framework. Versions prior to 4.00 were written for the X Window System and Motif.

Xfig is a free and open-source vector graphics editor which runs under the X Window System on most UNIX-compatible platforms.

GPU-based terminal emulator

Rxvt (acronym for our extended virtual terminal) is a terminal emulator for the X Window System, and in the form of a Cygwin port, for Windows.

xMule (short for "X11 Mule") is a discontinued free client for the eDonkey peer-to-peer file sharing network intended to bring it to virtually all the major Unix platforms, with a particular emphasis on Linux.

Unix graph plotting software

NEdit, the Nirvana editor, is a text editor and source code editor for the X Window System. It has an interface similar to text editors on Microsoft Windows and Macintosh, rather than to older UNIX editors like Emacs. It was initially developed by Mark Edel for Fermilab and released under a restrictive licence, but later relicenced under the GPL-2.0-or-later (plus Motif clause) and became an independent open-source project maintained by a team of developers. Nedit was also distributed with the IRIX operating system.

In the X Window System, the program xwd (X Window dump) captures the content of a screen or of a window and optionally saves it into a file.

PDFedit is a free PDF editor for Unix-like operating systems (including Cygwin on top of Windows). It does not support editing protected or encrypted PDF files or word processor-style text manipulation, however.

Xkill is a utility program distributed with the X Window System that instructs the X server to forcefully terminate its connection to a client, thus "killing" the client. When run with no command-line arguments, the program displays a special cursor (usually a crosshair or a skull and crossbones) and displays a message such as

xawtv is software for watching and recording television and webcams with either a TV tuner or a Satellite receiver card (DVB-S). xawtv works on Unix-like operating systems, and is licensed under the GPL.