Internationalized Domain Names command line tool

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

C library that supports plugin printer driver for Ghostscript

https://www.linuxprinting.org/ijs/

Library to communicate with Apple iOS devices

https://www.libimobiledevice.org

Kevent based inotify compatible library

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

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

https://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/

Interface library to access tags for identifying languages

http://tagoh.bitbucket.org/liblangtag/

Lightweight Open Sound Control implementation

https://liblo.sourceforge.net/

Easy to use C/C++ seam carving library

https://liblqr.wikidot.com/

System independent dlopen wrapper

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

MPEG audio decoder library

https://www.underbit.com/products/mad/ https://codeberg.org/tenacityteam/libmad

A library encapsulating malsync

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

Multi-cipher cryptographic library (used in PHP)

https://mcrypt.sourceforge.net/

Library for handling media art

https://www.gnome.org/

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

https://mikmod.sourceforge.net/

Multiple-image Network Graphics (MNG) reference library

https://www.libmng.com/

ModPlug mod-like music shared libraries

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

Abstraction around libmpdclient

http://gmpc.wikia.com/

API library for interfacing MPD

https://www.musicpd.org/libs/libmpdclient/

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/

NAT-PMP lightweight library

http://miniupnp.free.fr/

C library for creating IP packets

https://github.com/libnet/libnet

Library and transmitter that implements ICE-19

https://nice.freedesktop.org

Library and transmitter that implements ICE-19

http://nice.freedesktop.org/

Library and transmitter that implements ICE-19

https://nice.freedesktop.org

C library, API for communicating with Creative and Dell audio players

http://libnjb.sourceforge.net/

Library for desktop notifications

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

Astronomical Calculation Library

https://libnova.sourceforge.net/

Library that implement Microsoft's NTLM authentication

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

C library implementing the OAuth Core standard

http://liboauth.sourceforge.net/

Replacement Objective-C runtime supporting modern Objective-C features

https://github.com/gnustep/libobjc2/

Open Fingerprint Architecture Library

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

OpenSource implementation of the OFX (Open Financial eXchange)

https://libofx.sourceforge.net/

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 camera RAW files decoding

https://libopenraw.freedesktop.org/

Freedesktop synchronization framework

http://www.opensync.org/

Library for handling OpenType fonts

https://www.nongnu.org/m17n/

Portable OTR Messaging Library and toolkit

https://otr.cypherpunks.ca/

Library providing routines for paper size management

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

Ubiquitous network traffic capture library

https://www.tcpdump.org/