GGI API for input sources

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

Support library for gnome cups admistration

http://www.gnome.org/

Programming reference for print/libgnomeprint

http://www.gnome.org/projects/gnome-print/

Common error values for all GnuPG components

https://www.gnupg.org/software/libgpg-error/

Universal digital camera control library

http://www.gphoto.org/proj/libgphoto2/

GNOME top library

https://gitlab.gnome.org/GNOME/libgtop

Implementation of the IETF Calendaring and Scheduling protocols

https://github.com/libical

Character set conversion library

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

ID3 tags library (part of MAD project)

http://mad.sourceforge.net/

Internationalized Domain Names command line tool

http://www.gnu.org/software/libidn

C library that supports plugin printer driver for Ghostscript

http://www.linuxprinting.org/ijs/

Kevent based inotify compatible library

https://github.com/libinotify-kqueue/libinotify-kqueue

ODBC 3.x driver manager, for universal data source access

http://www.iodbc.org/

Library for Evation's Irman infrared receiver

https://libirman.sourceforge.io/

Standalone client/server 9P library

https://libs.suckless.org/deprecated/libixp/

Codec for karaoke and text encapsulation for Ogg

https://wiki.xiph.org/index.php/OggKate

Library to make X.509 certificates

https://www.gnupg.org/aegypten2/

Lightweight Open Sound Control implementation

http://liblo.sourceforge.net/

Easy to use C/C++ seam carving library

http://liblqr.wikidot.com/

System independent dlopen wrapper

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

Libmad library (part of MAD project)

https://www.underbit.com/products/mad/

A library encapsulating malsync

http://jasonday.home.att.net/code/libmal/

Multi-cipher cryptographic library (used in PHP)

http://mcrypt.sourceforge.net/

C library for accessing a memcache cluster

https://people.FreeBSD.org/~seanc/libmemcache/

Set of utilities to benchmark productivity of system calls

http://hub.opensolaris.org/bin/view/Project+libmicro/

MikMod Sound Library

http://mikmod.sourceforge.net/

Multiple-image Network Graphics (MNG) reference library

https://www.libmng.com/

ModPlug mod-like music shared libraries

http://modplug-xmms.sourceforge.net/

High quality audio compression format

http://www.musepack.net/

Abstraction around libmpdclient

http://gmpc.wikia.com/

Free library for decoding mpeg-2 and mpeg-1 video streams

http://libmpeg2.sourceforge.net/

Library for Microsoft compression formats

https://www.cabextract.org.uk/libmspack/

MusicBrainz client library for audio metadata lookup

http://musicbrainz.org/

MusicBrainz client library for audio metadata lookup

http://musicbrainz.org/

C library for creating IP packets

https://sourceforge.net/projects/libnet-dev/

Astronomical Calculation Library

http://libnova.sourceforge.net/

Library that implement Microsoft's NTLM authentication

https://www.nongnu.org/libntlm/

Open Fingerprint Architecture Library

http://code.google.com/p/musicip-libofa/

Ogg bitstream library

https://www.xiph.org/ogg/

Library of optimized inner loops

https://liboil.freedesktop.org/wiki/

Old X library

http://www.freedesktop.org/Software/xlibs

Library for handling OpenType fonts

http://www.nongnu.org/m17n/

Library providing routines for paper size management

https://packages.qa.debian.org/libp/libpaper.html

Ubiquitous network traffic capture library

https://www.tcpdump.org/

libpcap wrapper library

http://netdude.sourceforge.net/

PCI configuration space I/O made easy

https://mj.ucw.cz/sw/pciutils/

Generic PCI access library

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

Library to handle Apple Property List format

http://www.libimobiledevice.org

Library that provides automatic proxy configuration management

https://libproxy.github.io/libproxy/

Weak aliases for pthread functions

https://xcb.freedesktop.org/