It basically wraps some functionalities of quantlib library into an API. Main reason of it is that I think part of the target of the library is people that not need to know about programming, and an API opens it to future user friendly interfaces (such as the google sheets addon).

Examples, the add-on uses it and you can find the source code in the repository. Close source, yes now, it's been just a side project. Not thinking about monetize it now.