The NetWeaver inference engine was developed at Penn State University by Michael C. Saunders and Bruce J. Miller. Initial development of the system began in 1987, but the system has been steadily evolving ever since that time. It was originally developed for the Macintosh (tm Apple Computer) but has since been ported to Windows, Unix, MacOS, Android, iOS, and WebAssembly. 

The Windows NetWeaver development system (the visual interface) was developed at Rules of Thumb, inc. in order to provide efficient interactive access to the NetWeaver inference engine on the Windows platforms.