Project Builder

Project Builder was an integrated development environment (IDE) originally developed by NeXT for the NeXTSTEP operating system. It was rewritten and informally dubbed PBX while distributed by Apple Computer for software development on Mac OS X computer systems prior to Mac OS X v10.3. It was superseded by Xcode, as of Mac OS X 10.3 Panther.
GNUstep's ProjectCenter IDE is a rough workalike of the original NextStep design; additional functionality is provided by ProjectManager, a 3rd-party GNUstep IDE meant for greater usability.