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
an open source, high performance library for simulating rigid body dynamics. It is fully featured, stable, mature and platform independent with an easy to use C/C++ API. It has advanced joint types and integrated collision detection with friction.
The MLib (pronounced "M-Lib") is a C software framework that significantly simplifies the development of highly reliable system-level libraries and programs (like daemons/services). It is small, efficient, robust and highly portable, and was designed primarily for embedded systems. (From the FreeType project)
Pantheios is an Open Source C/C++ Logging API library, offering an optimal combination of 100% type-safety, efficiency, genericity and extensibility. It is simple to use and extend, highly-portable (platform and compiler-independent) and, best of all, it upholds the C tradition of you only pay for what you use.
CLAM stands for C++ Library for Audio and Music and in Catalan means something like "a continuous sound produced by a large number of people as to show approval or disapproval of a given event".
CLAM is a full-fledged software framework for research and application development in the Audio and Music Domain. It offers a conceptual model as well as tools for the analysis, synthesis and processing of audio signals.
software font engine that is designed to be small, efficient, highly customizable, and portable while capable of producing high-quality output (glyph images). It can be used in graphics libraries, display servers, font conversion tools, etc...
a multi-platform game library for C/C++ developers that provides many functions for graphics, sounds, player input (keyboard, mouse, and joystick), and timers.