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
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 multi-platform game library for C/C++ developers that provides many functions for graphics, sounds, player input (keyboard, mouse, and joystick), and timers.
a library of functions and a framework to interface with crypto algorithms provided by the calling application, built-in, or provided through shared libraries.
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.
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.