HubHip: Computers: Programming: Languages: Objective-C: Compilers and Environments (6)

GNUstep (Site) - A GNU project to write a completely OpenStep compatible programming environment based on Objective-C, with intentions to also maintain Mac OS X compatibility.
The MiscKit Frameworks (Site) - A free collection of Objective-C objects useful to Rhapsody, OPENSTEP, GNUstep, and NeXTSTEP programmers.
ActiveDeveloper (Site) - Interactive runtime Objective-C IDE for Windows, Mac OS X, OpenStep NIS.
Portable Object Compiler (Site) - A preprocessor that will convert Objective-C into regular C.
Cocoa (Site) - Apple's Objective-C based programming environment for Mac OS X.
OpenStep Specification (Site) - A copy of NeXT Computer's OpenStep Specification. This is the specification that both Cocoa and GNUstep are based on.