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

http://www.iodbc.org/

Library for manipulating IPTC metadata stored in image files

http://libiptcdata.sourceforge.net/

Library for Evation's Irman infrared receiver

https://libirman.sourceforge.io/

Libburnia ISO9660 filesystem creation library

https://dev.lovelyhq.com/libburnia/web/wikis/home

Standalone client/server 9P library

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

SIMD-accelerated JPEG codec library, provides libTurboJPEG

http://libjpeg-turbo.virtualgl.org/

JPEG XL reference encoder/decoder

https://jpeg.org/jpegxl/

KDE CDDB library

https://www.kde.org/

KDE library for interfacing with audio CDs

https://www.kde.org/

LibRaw interface for KDE

https://invent.kde.org/graphics/libkdcraw

Libraries used by KDE games

https://www.kde.org/applications/games/

Library for reading and writing vocabulary files

https://edu.kde.org/

Exiv2 library interface for KDE

https://www.digikam.org/

Certificate manager for KDE

https://www.kde.org/applications/utilities/kleopatra/

Library for the Mahjongg Solitaire for KDE

https://www.kde.org/applications/games/kmahjongg/

Engine to interpret compiled KMFL keyboard tables

https://kmfl.sourceforge.net/

Reference implementation of OGC KML 2.2

https://github.com/libkml/libkml

Kolab XML Format Schema Definitions Library

https://kolab.org/

KSBA is an X.509 Library

http://www.gnupg.org/aegypten2/

Interface library to access tags for identifying languages

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

Lightweight KMS plane library

https://gitlab.freedesktop.org/emersion/libliftoff

Lightweight Open Sound Control implementation

http://liblo.sourceforge.net/

Standard lockfile library

https://github.com/miquels/liblockfile

Easy to use system logging library

https://www.liblogging.org/

Easy to use C/C++ seam carving library

http://liblqr.wikidot.com/

Library for manipulating RDF files describing LADSPA plugins

https://github.com/swh/LRDF

System independent dlopen wrapper

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

LZ4 compression library, lossless and very fast

http://www.lz4.org/

Provides a few data structures and helpful functions

https://github.com/cheusov/libmaa

Libmad library (part of MAD project)

http://mad.sourceforge.net/

MATE keyboard shared library

https://mate-desktop.org/

Mixer library for MATE desktop

https://github.com/mate-desktop/libmatemixer

Library to accessing online weather informations

https://mate-desktop.org/

Extensible Multimedia Container Format

https://www.matroska.org/

Library for the MaxMind DB file format used for GeoIP2

https://github.com/maxmind/libmaxminddb

Multi-cipher cryptographic library (used in PHP)

http://mcrypt.sourceforge.net/

Library for handling media art

https://www.gnome.org/

MediaInfo library

https://mediaarea.net/en/MediaInfo https://github.com/MediaArea/MediaInfoLib

C library for accessing a memcache cluster

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

C and C++ client library to the memcached server

http://libmemcached.org

Set of utilities to benchmark productivity of system calls

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

C library for embedding HTTP server functionality

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

MikMod Sound Library

http://mikmod.sourceforge.net/

Library providing Sendmail Mail Filter API

http://www.sendmail.com/sm/open_source/milter/

Multiple-image Network Graphics (MNG) reference library

http://www.libmng.com/

Modbus library

https://libmodbus.org/

Library and tools to access the Mac OS disk image formats

https://github.com/libyal/libmodi

ModPlug mod-like music shared libraries

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

Perl module to manipulate filenames containing music metadata

https://erislabs.net/ianb/projects/libmp3-archive-perl/

Abstraction around libmpdclient

http://gmpc.wikia.com/