Communication interface library for usbmuxd

http://www.libimobiledevice.org

The uTorrent Transport Protocol library and sample utilities

https://github.com/bittorrent/libutp

Library to generate or parse 128-bit Universally Unique IDs (UUIDs)

https://github.com/util-linux/util-linux

Multi-platform support library with a focus on asynchronous I/O

https://github.com/libuv/libuv

Cross-platform library for USB video devices

https://libuvc.github.io/libuvc/

Video4Linux library

http://freshmeat.net/projects/libv4l

VAAPI wrapper and dummy driver

https://github.com/intel/libva

VAAPI wrapper for GLX

https://github.com/intel/libva

VDPAU wrapper and tracing library

http://freedesktop.org/wiki/Software/VDPAU

Toolkit to interact with virtualization capabilities

https://libvirt.org/

Glib bindings for Libvirt virtualization API

http://www.libvirt.org

Library and tools for parsing the visio file format structure

https://wiki.documentfoundation.org/DLP/Libraries/libvisio

Abstraction library that sits between apps and visual plugin

http://libvisual.sourceforge.net/

Provide an easy API to a custom vnc server

http://libvnc.github.io/

Audio compression codec library

https://xiph.org/vorbis/

VP8/VP9 reference encoder/decoder

https://www.webmproject.org/

Implementation of a VT220/xterm/ECMA-48 terminal emulator

https://www.leonerd.org.uk/code/libvterm/

Adds tablet support to libinput

http://linuxwacom.sourceforge.net/wiki/index.php/Libwacom

String internment library

http://www.netsurf-browser.org/projects/libwapcaplet/

C library for lightweight websocket clients and servers

https://libwebsockets.org/

Tools and library for converting Microsoft WMF (windows metafile)

http://wvware.sourceforge.net/libwmf.html

Tools and library for converting Microsoft WMF (windows metafile)

http://wvware.sourceforge.net/libwmf.html

Library used for writing pagers and taskslists

https://www.gnome.org/

Library used for writing pagers and taskslists

http://www.gnome.org/

Tools for importing and exporting WordPerfect(tm) documents

http://libwpd.sourceforge.net/

Tools for importing and exporting WordPerfect(tm) documents

http://libwpd.sourceforge.net/

General-purpose library for WPE WebKit

https://wpewebkit.org/releases

Library and tools to work with WordPerfect Graphics (WPG) files

https://libwpg.sourceforge.net/

Window Maker raster graphics library

http://www.windowmaker.org/

The W3C Reference Library

http://www.w3.org/Library/

Library for encoding H.264/MPEG-4 AVC video

http://www.videolan.org/x264.html

3D Xaw (Athena Widget Set) replacement with extended fonts

https://sourceforge.net/projects/sf-xpaint/files/

The X protocol C-language Binding (XCB) library

https://xcb.freedesktop.org/

Extended crypt library for descrypt, md5crypt, bcrypt, and others

https://github.com/besser82/libxcrypt

Calculate VESA CVT mode lines

https://gitlab.freedesktop.org/xorg/lib/libxcvt

Implementation of the XDG Base Directory specification

http://n.ethz.ch/student/nevillm/download/libxdg-basedir/

Widgets library for the Xfce desktop environment

https://www.xfce.org/

Extension library for the Xfce desktop environment

https://www.xfce.org/

Windowing concept abstraction library for X11 and Wayland

https://gitlab.xfce.org/xfce/libxfce4windowing

Libraries for xine multimedia player

http://www.xine-project.org/

Keymap handling library for toolkits and window systems

https://xkbcommon.org/

XKB file library

https://www.freedesktop.org/Software/xorg

Utility library to make XKB stuff easier

http://gswitchit.sourceforge.net/

XML API for C++

http://libxmlplusplus.sourceforge.net/

XML parser library for GNOME

http://xmlsoft.org/

Python interface for XML parser library for GNOME

http://xmlsoft.org/

Library to help create and query binary XML blobs

https://github.com/hughsie/libxmlb

Module rendering library for xmp

http://xmp.sourceforge.net/

XSD runtime library

https://www.codesynthesis.com/projects/xsd/

W3C XML Schema compiler frontend

https://www.codesynthesis.com/projects/libxsd-frontend/