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/

Multitouch Protocol Translation Library

http://bitmath.org/code/mtdev/

Media Transfer Protocol (MTP) library

http://libmtp.sourceforge.net/

MusicBrainz client library for audio metadata lookup

http://musicbrainz.org/

MusicBrainz client library for audio metadata lookup

http://musicbrainz.org/

Brush library from the MyPaint project

http://mypaint.org/

NAT-PMP lightweight library

http://miniupnp.free.fr/

C library for creating IP packets

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

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

Library for desktop notifications

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

Astronomical Calculation Library

http://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)

http://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

Wrapping library to the System Tools Backends

Library for camera RAW files decoding

http://libopenraw.freedesktop.org/

Freedesktop synchronization framework

http://www.opensync.org/

Library for handling OpenType fonts

http://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/

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/

Next evolution of the Gedit plugins engine

http://live.gnome.org/libpeas

Library to handle Apple Property List format

http://www.libimobiledevice.org

Library for transforming bitmaps into vector graphics

http://potrace.sourceforge.net

Library that provides automatic proxy configuration management

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

Weak aliases for pthread functions

https://xcb.freedesktop.org/

Library for generating random passwords and quality checking

https://github.com/libpwquality/libpwquality

Multi-purpose desktop calculator (backend library)

http://qalculate.github.io/

C library for encoding data in a QR Code symbol

http://megaui.net/fukuchi/works/qrencode/index.en.html

Cross-platform library for parsing flash media stream URLs

http://quvi.sourceforge.net/

Embedded lua scripts for libquvi and utility scripts

http://quvi.sourceforge.net/

Embedded lua scripts for libquvi and utility scripts

http://quvi.sourceforge.net/

Cross-platform library for parsing flash media stream URLs

http://quvi.sourceforge.net/

Library for manipulating raw images

https://www.libraw.org/

Free version of the SSL/TLS protocol forked from OpenSSL

http://www.libressl.org/

Easy access to RESTful web services

https://wiki.gnome.org/Projects/Librest

Base library for writing document import filters

http://libwpd.sourceforge.net

Library for parsing and rendering SVG vector-graphic files

http://live.gnome.org/LibRsvg

RTMP stream library

https://rtmpdump.mplayerhq.hu/