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

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/

Magnify, rotate, mirror the image on the X screen

Yet another Basic for Unix and Windows

http://www.yabasic.de/

Display GNOME dialogs from the command line

https://github.com/v1cont/yad

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/

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/

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/

Default GTK theme for Ubuntu

https://github.com/ubuntu/yaru

Default icon theme for Ubuntu

https://github.com/ubuntu/yaru

Complete rewrite of the NASM assembler

https://yasm.tortall.net/

General-purpose console screen reader

http://yasr.sourceforge.net/

Z39.50/SR client and API library

https://www.indexdata.com/resources/software/yaz/

Diff readability enhancher for color terminals

https://github.com/ymattw/ydiff

Terminal wrapper for creating drop-down consoles

http://phrat.de/yeahtools.html

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/

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/

Unpack data in MS Outlook TNEF format

https://github.com/Yeraze/ytnef

Yubico PIV tool

https://developers.yubico.com/yubico-piv-tool/

The Yahoo! JavaScript and CSS Compressor

https://yui.github.io/yuicompressor/

Tool to decode yEnc encoded files

http://yydecode.sf.net/

ZBar barcode reader

http://zbar.sourceforge.net

Encrypted, secure compressed TCP tunnel

http://www.winton.org.uk/zebedee/

Free RIPv1, RIPv2, OSPFv2, BGP4 route software (server/reflector)

http://www.zebra.org/

Z39.50/SR server software

http://www.indexdata.dk/zebra/

Event logging framework

https://wiki.gnome.org/Projects/Zeitgeist

Framework for developing PHP web applications

https://framework.zend.com/

Display GNOME dialogs from the command line

Simpler web photo gallery

https://www.zenphoto.org/

Network virtualization everywhere

https://www.zerotier.com/

Zetaback ZFS backup and recovery management system

https://github.com/omniti-labs/zetaback/

Simple way of maintaining zfs snapshots using the periodic system

http://www.neces.com/blog/technology/integrating-freebsd-zfs-and-periodic-snapshots-and-scrubs

ZFS Snapshot Replication Script

https://github.com/leprechau/zfs-replicate

Tool to sieve ZFS snapshots as per given spec a la 'pdumpfs-clean'

https://github.com/knu/zfs-snapshot-clean

Automatic ZFS snapshot management tool

http://marcin.studio4plus.com/en/zfs-file-history/howto.html

Display human-readable ZFS statistics

http://www.vx.sk/zfs-stats/

Simple sh script to make zfs rolling snaphosts with cron

https://github.com/graudeejs/zfSnap/

OpenSolaris-compatible auto snapshotting for ZFS

https://github.com/bdrewery/zfstools