Universal configuration library parser

https://github.com/vstakhov/libucl

libudev-compatible interface for devd

https://github.com/wulf7/libudev-devd

Library to manipulate storage devices, from udisks

https://www.freedesktop.org/wiki/Software/udisks/

Implementation of the line and word breaking algorithm for Unicode

https://vimgadgets.sourceforge.net/libunibreak/

Library for manipulating Unicode characters and strings

https://www.gnome.org/

Library of Unicode annotation data

http://libuninameslist.sourceforge.net/

Library for converting Unicode strings to numbers

http://billposer.org/Software/libuninum.html

Library for single instance applications

https://wiki.gnome.org/Attic/LibUnique

Unicode string library

https://www.gnu.org/software/libunistring/

Library to work with RAR archivies

http://www.rarsoft.com/

Generic stack unwinding library

https://www.nongnu.org/libunwind/

Userspace read-copy-update (RCU) data synchronization library

http://lttng.org/urcu

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

https://linuxtv.org/wiki/index.php/V4l-utils

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

https://github.com/linuxwacom/libwacom/wiki

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

http://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

https://github.com/devnev/libxdg-basedir/

Widgets library for the Xfce desktop environment

https://www.xfce.org/

Extension library for the Xfce desktop environment

https://www.xfce.org/