The only way for an application development framework to be classed as "rapid" is to provide the ability to assemble application components from a library of pre-written and reusable parts. I am not aware of any other open-source framework which provides anywhere near the same levels of reusability as RADICORE.
A short description of how this framework was created can be found at
The Road to Rapid Application Development (RAD)
A longer description, starting with the version I built in COBOL in the 1980s, can be found at
Evolution of the RADICORE framework
Here are some online tutorials and some videos.
