Standard library for Window Maker dock apps

http://solfertje.student.utwente.nl/~dalroi/libdockapp/

Userspace interface to kernel Direct Rendering Module services

https://dri.freedesktop.org/

Alsa compatibility library to build DSSI

http://www.smbolton.com/linux.html

Quasar DV codec (libdv): software codec for DV video encoding format

http://libdv.sourceforge.net/

Portable abstraction library for DVD decryption

https://www.videolan.org/developers/libdvdcss.html

Videolan version of the libdvdnav project

https://www.videolan.org/developers/libdvdnav.html

MPlayer version of the libdvdread project

https://www.videolan.org/developers/libdvdnav.html

Command line editor library

http://thrysoee.dk/editline/

Enhanced Metafile Library

http://libemf.sourceforge.net/

Library to handle OpenGL function pointer management

https://github.com/anholt/libepoxy

Liberation fonts from Red Hat to replace MS TTF fonts

https://github.com/liberationfonts/liberation-fonts

Full-featured and high-performance event loop library

http://software.schmorp.de/pkg/libev.html

API for executing callback functions on events or timeouts

http://libevent.org/

Library for inspecting program's backtrace

http://www.gnu.org/software/libc/manual/html_node/Backtraces.html

Library to read digital camera file meta-data

https://libexif.github.io/

Application library for the Xfce desktop environment

https://www.xfce.org/

Video encoding library

http://fame.sourceforge.net/

Foreign Function Interface

https://sourceware.org/libffi/

The fontenc Library

https://www.x.org/

Library routines for working with Flashpix images

https://www.i3a.org/

Library (using libusb) to talk to FTDI chips

http://www.intra2net.com/de/produkte/opensource/ftdi/

General purpose crypto library based on code used in GnuPG

https://www.gnupg.org/software/libgcrypt/index.html

Provides uniform access to different kinds of data sources

http://www.gnome-db.org/

GDI+ API for System.Windows.Forms in Mono

https://www.mono-project.com/docs/gui/libgdiplus/

GObject collection library

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

The GGZ Gaming Zone - Base Library

http://www.ggzgamingzone.org/

Portable, pure C implementation of the Git core

https://libgit2.github.com/

Glib wrapper library around the libgit2 git access library

https://git.gnome.org/browse/libgit2-glib

GNOME glade library

Common GL api library used by Mesa based ports

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

OpenGL ES v2 library

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

Collection of video game music emulators

https://bitbucket.org/mpyne/game-music-emu

Libraries for GNOME, a GNU desktop environment

http://www.gnome.org/

Program that keeps passwords and other secrets

Graphics library for GNOME

Support library for gnome cups admistration

http://www.gnome.org/

GNOME keyboard shared library

Gnome print support library

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

Programming reference for print/libgnomeprint

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

C++ bindings for the GNOME print support library

Gnome print support library

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/

Extensible i/o abstraction for dealing with structured file formats

http://www.gnumeric.org

GNOME top library

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

Library to access online weather informations

http://www.gnome.org/

GObject based library for rendering XPS documents

https://wiki.gnome.org/action/show/Projects/libgxps

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/