SOFA (Spatially Oriented Format for Acoustics) file reader

https://github.com/hoene/libmysofa

NAT-PMP lightweight library

http://miniupnp.free.fr/

C library for creating IP packets

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

Client library for accessing NFS shares over a network

https://github.com/sahlberg/libnfs

HTTP/2.0 C Library

https://nghttp2.org/

Library and transmitter that implements ICE-19

https://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

http://libnova.sourceforge.net/

NetSurf BMP decoder

http://www.netsurf-browser.org/projects/libnsbmp/

NetSurf GIF Decoder

http://www.netsurf-browser.org/projects/libnsgif/

NetSurf public suffix list handling

https://www.netsurf-browser.org/

NetSurf generalised utility library

http://www.netsurf-browser.org/

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/

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/

Wrapping library to the System Tools Backends

Module music library based on OpenMPT

https://lib.openmpt.org/

Freedesktop synchronization framework

http://www.opensync.org/

C++ implementation of an OpenID decentralized identity system

http://kin.klever.net/libopkele/

Library for managing OS information for virtualization

https://libosinfo.org/

Off-Screen Mesa implementation of the OpenGL API

https://www.mesa3d.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

Lexer/parser utility functions for NetSurf

http://www.netsurf-browser.org/projects/libparserutils/

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

Reusable library for GPU-accelerated video/image rendering

https://code.videolan.org/videolan/libplacebo

Library to handle Apple Property List format

http://www.libimobiledevice.org

GIO-styled async APIs for Flatpak

https://github.com/flatpak/libportal

GIO-styled async APIs for Flatpak

https://github.com/flatpak/libportal

GIO-styled async APIs for Flatpak

https://github.com/flatpak/libportal

GIO-styled async APIs for Flatpak

https://github.com/flatpak/libportal

Library for transforming bitmaps into vector graphics

http://potrace.sourceforge.net

Library that provides automatic proxy configuration management

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

C library to handle the Public Suffix List

https://github.com/rockdaboot/libpsl

Weak aliases for pthread functions

https://xcb.freedesktop.org/

Backend library for the Pidgin multi-protocol messaging client

https://www.pidgin.im/

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/