Brace is a dialect of C that looks like Python. It has coroutines, hygenic macros, header generation, and libraries with graphics and sound. It is meant to be good for beginners, kids, and experts. Brace is translated to C, then compiled, with #! support and cached executables. It is fairly portable, and runs on GNU/Linux, Unix, and Windows with MinGW. It should also run on Mac OS X. It comes with a lot of demo programs, many with animated graphics.
Goptical is the GNU Optical design and simulation library. It provides model classes for optical components, surfaces, and materials and enables building of optical systems by creating and placing various optical components in a 3D space and simulating light propagation through the system. Classical optical design analysis tools can be used on optical systems. It takes advantages of the C++ object model to allow the building of complex optical systems with a few class instantiations, as optical components are represented by language objects.
libvalhalla is a library written in C. It is a media scanner that stores various information in an SQLite database and relies on FFmpeg (libavformat and libavutil) and libcurl. It features many Internet grabbers that allow automatic downloading of covers, lyrics, and information on media files, tag retrieval in video and music files, and so on.
D'Enfent Engine is a library that contains high-level classes to access OpenGL functions. It contains classes that may be very useful in game development: GUI components, sprite classes, and classes to handle mouse/keyboard events. It has a full API reference, as well as lessons to help you start working with the library.
[fleXive] CMS is a Java EE content management system based on JavaServer Faces 1.2. It combines the power of JSF XHTML templating with that of the Java EE 5 content repository, [fleXive]. Some highlights include dynamic JSF templating (Facelets), easy integration of custom logic with EJB or JSF beans, a modular structure, Maven support, generic data structures, and WebDAV and CMIS support. It incorporates all core [fleXive] features like security, versioning, multilinguism, and scripting.
DDMSence (pronounced "dee-dee-em-Essence") is a Java API that supports the DoD Discovery Metadata Specification (DDMS). It provides a complete implementation of the DDMS specification using DDMS 2.0, 3.0, 3.1, 4.0.1, or 4.1. Validation is performed according to both the schema and the specification, and custom validation rules can be defined with ISO Schematron.
C++ command line parameters parser (CLPP) is a command line parameter parser with callback functions and, if necessary, type/semantic checking of values of input parameters. It uses only Boost C++ libraries and ISO C++. It is header-only (no need to build it) and very simple to use.