Calc is arbitrary precision arithmetic system that uses a C-like language. It's useful as a calculator, an algorithm prototype, and as a mathematical research tool. More importantly, calc provides a machine-independent means of computation. Calc comes with a rich set of builtin mathematical and programmatic functions.
ccaudio2 is a simple, highly portable, stand-alone, C++-based framework for manipulation of audio data. Its goal is to be a C++ framework that is as useful as "audiofile" or "sndfile" is for C programming, and to cover various generic and useful manipulations of audio data as well as audio file access. A stand-alone audio processing command line tool is also provided to demonstrate library functionality. ccaudio2 compiles under Mac OS X, POSIX systems, and Win32 systems.
Common C++ is a highly portable C++ class library meant primarily for the development of portable threaded applications. Support is provided both for POSIX platforms and native builds under Win32. The goal is to provide a truly common C++ framework for writing portable threaded applications that do not require a huge amount of runtime overhead to support, and hence can make C++ and threads suitable even for the development of trivial servers and applications.
Common C++ RTP is an experimental threadsafe RTP stack for use with Common C++. It uses a service thread to both schedule outgoing packets and organize arriving packets. Queued lists of packets are maintained both for sending and receiving, and packet payloads can be mixed such as for passing RTP telephony events. Recent builds of GNU ccRTP are also available for building handheld softphone clients using Open Embedded.
CUPS is a standards-based printing system for Mac OS X and other Unix-like operating systems. It provides the System V and Berkeley command line interfaces, and uses the Internet Printing Protocol ("IPP") as the basis for managing print jobs and queues. The Line Printer Daemon (LPD) Server Message Block (SMB), and AppSocket (a.k.a. JetDirect) protocols are also supported with reduced functionality. CUPS adds network printer browsing and PostScript Printer Description ("PPD") based printing options to support real world printing.
curl and libcurl is a tool for transferring files using URL syntax. It supports HTTP, HTTPS, FTP, FTPS, SCP, SFTP, TFTP, DICT, TELNET, LDAP, POP3, IMAP, SMTP, RTSP, RTMP, and FILE, as well as HTTP-post, HTTP-put, cookies, FTP upload, resumed transfers, passwords, port numbers, SSL certificates, Kerberos, and proxies. It is powered by libcurl, the client-side URL transfer library. There are bindings to libcurl for about 40 languages and environments.
db4o is an object database for Java and all .NET environments. Its features include ACID transactions, automatic class schema recognition, query-by-example, a S.O.D.A. object querying API, native queries, LINQ support on .NET, callback methods, memory files, cascade-on-delete, multi-threaded access, and Java Webstart and servlet support.
FLTK (pronounced "fulltick") is a cross-platform C++ GUI toolkit for UNIX/Linux (X11), Microsoft Windows, and Mac OS X. It provides modern GUI functionality without the bloat, and supports 3D graphics via OpenGL and its built-in GLUT emulation. FLTK is designed to be small and modular enough to be statically linked, and also works fine as a shared library. It also includes an excellent UI builder called FLUID that can be used to create applications in minutes.
getmail is intended as a simple, secure, and reliable replacement for fetchmail. It retrieves email (either all messages, or only unread messages) from one or more POP3, SPDS, or IMAP4 servers (with or without SSL) for one or more email accounts, and reliably delivers into qmail-style Maildirs, mboxrd files, or through external MDAs (command deliveries) specified on a per-account basis. getmail also has excellent support for domain (multidrop) mailboxes, including delivering messages to different users or destinations based on the envelope recipient address.