GNUstep is a mature Framework, suited both for advanced GUI desktop applications as well as server applications. The framework closely follows Apple's Cocoa (formerly NeXT's OpenStep) APIs but is portable to a variety of platforms and architectures.
Read more about the GNUstep project, or the people behind it.
GNUstep offers Development tools for command-line and GUI development, as well as the foundations for a Desktop environment, which other projects can complete.
GNUstep provides the foundations for a portable desktop environment,
but delegates this task to other projects, like:
GNUstep provides an environment to easily develop
advanced GUI desktop applications as well as server applications.
GNUstep's core framework provides open source version of the Cocoa's (formerly known as OpenStep from NeXT) APIs and tools for as many platforms as possible.
GNUstep provides a robust implementation of the AppKit and
Foundation libraries as well as the development tools
including the advanced interface designer Gorm (the InterfaceBuilder) and the IDE
Thematic instead provides a user-friendly accesso to theming.
GNUstep seeks to be source code compatible with Cocoa, it can
thus be used to develop and build cross-platform applications
between Macintosh (Cocoa), Unix (Solaris) and Unix-like (GNU/Linux and GNU/Hurd, NetBSD, OpenBSD, FreeBSD) platforms as well as Windows
GNUstep's main development language is Objective-C, but
GNUstep is not limited to that.