GNUstep is a cross-platform, object oriented environment composed of frameworks, tools, and servers (daemons). It is very similar to the Cocoa frameworks from Apple, and tries to maintain compatibility with Cocoa wherever it is desired and possible. The frameworks provide classes for containers, distributed objects, object archiving, file management, text system, font management, image composition, WYSIWYG PostScript graphics, and more.
GPP is a general-purpose preprocessor with customizable syntax, suitable for a wide range of preprocessing tasks. Its independence from any programming language makes it much more versatile than cpp, while its syntax is lighter and more flexible than that of m4. The syntax is fully customizable, which makes it possible to process text files, HTML, or source code equally efficiently in a variety of languages.
The SOPE package is an extensive set of frameworks (16 frameworks, ~1500 classes) which form a complete Web application server environment. Besides the Apple WebObjects compatible appserver extended with Zope concepts, it contains a large set of reusable classes: XML processing (SAX, DOM, XML-RPC), MIME/IMAP4 processing, LDAP connectivity, RDBMS connectivity, and iCalendar parsing. The parts of the package can be used stand-alone (e.g. in Cocoa applications) and do not require the appserver parts. For MacOSX developers, the package includes SOPE:X, which contains special Xcode and Cocoa support for SOPE.
Addresses is a GNUstep address book that consists of a full-featured address book manager application, a source-code compatible replacement for Apple's AddressBook.framework (for accessing and manipulating address data programmatically), a framework of view/editor classes that make it easy to use Addresses from your own programs, and a number of tools. It is easy to use by both users and programmers and can store almost all imaginable data, including multiple phone numbers, emails, and addresses, photos, AIM/Jabber/ICQ/Yahoo IM details, and notes. It supports drag-and-drop and integrates well with GNUMail.
mGSTEP is a software development framework designed primarily for use in embedded devices. It implements the core elements of NeXT's OpenStep that evolved into Apple's Cocoa Objective-C class libraries. The drawing API is a partial implementation of Display Postscript in parallel with the newer Core Graphics API. The stable GUI (AppKit) is X11 based. A Linux framebuffer based GUI backend is also included.