Faust is a functional programming language specifically designed for realtime audio applications and plugins. The syntax of the language is block diagram oriented. The faust compiler translate signal processing specifications into optimized C++ code for signal processing applications.

fcft is a small font loading and glyph rasterization library built on-top of FontConfig, FreeType2 and pixman.

flatzebra is a simple generic C++ game engine library supporting 2D double-buffering.

OpenJDK is a development environment for building applications, applets, and components using the Java programming language.

Flickcurl is a C library for the Flickr API, handling creating the requests, signing, token management, calling the API, marshalling request parameters and decoding responses. The library now supports 100% of the 2008-01-11 version of the API, including the functions for photo uploading, browsing, searching, adding and editing comments, groups, notes, photosets, categories, activity, blogs, favorites, places, tags and photo metadata. It also includes a program flickrdf to turn photo metadata, tags and machine tags into RDF descriptions of photos and tags.

FlightCrew is an epub validator written in C++. It is used by sigil to validate epub files, and may be generally useful for other epub creation utilities.