a multi-platform game library for C/C++ developers that provides many functions for graphics, sounds, player input (keyboard, mouse, and joystick), and timers.
the XML C parser and toolkit developed for the Gnome project (but usable outside of the platform). Code is portable (to Linux, Unix, Windows, embedded systems, etc.) and modular; most of the extensions can be compiled out
a free (under GNU Lesser GPL) library which provides a uniform interface to a large number of hash algorithms. These algorithms can be used to compute checksums, message digests, and other signatures.
a library of functions and a framework to interface with crypto algorithms provided by the calling application, built-in, or provided through shared libraries.
is a layer above the existing toolkits available (Win32 API, GTK, Cocoa, ...). The result is that applications look and function like the user expects on their respective system. Mozilla Public License
a C library for reading and writing sound files such as AIFF, AU, WAV, and others through one standard interface. It can currently read/write 8, 16, 24 and 32-bit PCM files as well as 32 and 64-bit floating point WAV files and a number of compressed formats.