Print out X-Video extension adaptor information

Xwallpaper utility allows you to set image files as your X wallpaper

https://github.com/stoeckmann/xwallpaper

Watch a window on another X server

X Clients under Wayland

https://wayland.freedesktop.org/xserver.html

X11 server as Wayland client (development snapshot)

https://wayland.freedesktop.org/xserver.html

Dump an image of an X window

Window information utility for X

XWinWrap replace a desktop background with a movie or screensaver

http://tech.shantanugoel.com/projects/linux/shantz-xwinwrap

X interface tool

Classic game with apples and hungry worm

Image displayer for X

Extremely fast non-cryptographic hash algorithm

https://cyan4973.github.io/xxHash/

XKB keyboard layout indicator and switcher

https://sourceforge.net/projects/xxkb/

Puzzle games like sokoban or boulderdash

https://xye.sourceforge.net/

Infocom game interpreter that runs under X11

https://www.eblong.com/zarf/xzip.html

Magnify, rotate, mirror the image on the X screen

Yet another Basic for Unix and Windows

http://www.yabasic.de/

Original free open-source forum written in Perl

http://www.yabbforum.com/

Display GNOME dialogs from the command line

https://github.com/v1cont/yad

WAD file editor, for games like Doom and Heretic

http://www.teaser.fr/~amajorel/yadex/

Yet another FTP client, similar to ftp(1)

http://www.yafc-ftp.com/

Yet Another File Integrity Checker, similar to Tripwire

http://philosophysw.com/software/yafic/

Curses version of the dice game for one or more players

Portable JSON parsing and serialization library in ANSI C

http://lloyd.github.com/yajl/

Enhanced execution box with regex pattern matching

http://offog.org/code/

YAML parser and emitter in C++ matching the YAML 1.2 spec

https://github.com/jbeder/yaml-cpp

Package manager for node, alternative to npm (meta port)

https://classic.yarnpkg.com/

Package manager for node, alternative to npm

https://classic.yarnpkg.com/

Package manager for node, alternative to npm

https://classic.yarnpkg.com/

Package manager for node, alternative to npm

https://classic.yarnpkg.com/

Package manager for node, alternative to npm

https://classic.yarnpkg.com/

Default GTK theme for Ubuntu

https://github.com/ubuntu/yaru

Default icon theme for Ubuntu

https://github.com/ubuntu/yaru

POSIX-compliant command line shell

https://yash.osdn.jp/index.html.en

Complete rewrite of the NASM assembler

https://yasm.tortall.net/

General-purpose console screen reader

http://yasr.sourceforge.net/

Yet Another LaTeX mode and html mode on Emacs

http://www.yatex.org/

Diff readability enhancher for color terminals

https://github.com/ymattw/ydiff

Terminal wrapper for creating drop-down consoles

http://phrat.de/yeahtools.html

Minimal X11 window manager with BeOS-like tabbed titles

http://phrat.de/

Help browser for the GNOME 3 desktop

https://www.gnome.org/

Utilities to help manage documentation for Yelp and the web

https://wiki.gnome.org/Apps/Yelp/Tools

DocBook XSLT stylesheets for yelp

https://www.gnome.org/

Free (GPL) encoder and decoder for the yEnc Usenet file format

http://www.yencode.org/

Amateur Radio curses based logging program

https://fkurz.net/ham/yfklog.html

Convert between YAML, TOML, JSON, and HCL

https://github.com/sclevine/yj

Command line tool that converts YAML to JSON

https://github.com/bruceadams/yj

Yubico C client library

https://developers.yubico.com/yubico-c-client/

Library and tool for personalization of Yubico's YubiKey

https://developers.yubico.com/yubikey-personalization/

Command-line YAML and XML processor, jq wrapper for YAML/XML documents

https://github.com/kislyuk/yq