AFNIX is a multi-threaded functional writing system with dynamic symbol bindings that support the object oriented paradigm. It has a rich set of features providing runtime compatibility with C++. The engine runs on both 32- and 64-bit platforms, and it is designed to be portable across platforms.
ANTLR (ANother Tool for Language Recognition) is a language tool that provides a framework for constructing recognizers, compilers, and translators from grammatical descriptions containing C++, Java, or Sather actions. It is similar to the popular compiler generator YACC, however ANTLR is much more powerful and easy to use. ANTLR-produced parsers are not only highly efficient, but are both human-readable and human-debuggable (especially with the interactive ParseView debugging tool). ANTLR can generate parsers, lexers, and tree-parsers in either C++, Java, or Sather. ANTLR is currently written in Java.
Angel is a 2D game prototyping engine based on OpenGL and C++. It was originally made by a group of employees at Electronic Arts Los Angeles for use in a GameJam they were planning for April of 2008. Angel provides many useful functions for prototyping gameplay, including simple physics, particles, text rendering, sound, input mappings, config files, pathfinding, and Python scripting.
Aftpd is an FTP server for anonymous access designed for Unix-like operating systems. It uses an asynchronous model of connection processing and provides service for all users within a single process; can use multiple threads to run more efficiently on multi-core systems, with each thread serving multiple clients simultaneously; uses effective mechanisms of transferring files, minimizing copying of data in RAM (sendfile or a combination of the system calls mmap/writev); uses effective event notification schemes (kqueue on FreeBSD and epoll on Linux); uses poll or select in older systems; and supports IPv6. For safety, it works as an unprivileged user and uses chroot.
AweMUD is a MUD server for use with fantasy-settings. Features include fully dynamic objects and characters, an advanced scripting system, and custom worlds. The engine will eventually have completely interactive rooms (items can be placed under benches, doors can be destroyed), complex magick, and interactive NPCs.
Ayam is a free 3D modelling environment for the RenderMan interface. It features good RIB export, CSG (all RenderMan primitives supported), and NURBS modelling. Features instancing, arbitrary number of modeling views, object clipboard, independent property clipboard, n-level undo, console, and Tree-View with Drag-and-Drop support.
BRL-CAD is a powerful constructive solid geometry solid modeling system that includes an interactive geometry editor, ray-tracing support for rendering and geometric analysis, path-tracing for realistic image synthesis, network distributed framebuffer support, and image and signal-processing tools.