I found flask's documentation quite well-written in this regard. For example, they provide insights at how to grow your application's structure in several ways

I found flask's documentation quite well-written in this regard. For example, they provide insights at how to grow your application's structure in several ways: http://flask.pocoo.org/docs/becomingbig/ http://flask.pocoo.org/docs/becomingbig/, http://flask.pocoo.org/docs/patterns/packages/ http://flask.pocoo.org/docs/patterns/packages/ and http://flask.pocoo.org/docs/patterns/appfactories/ http://flask.pocoo.org/docs/patterns/appfactories/. Generally speaking, http://flask.pocoo.org/docs/patterns/ http://flask.pocoo.org/docs/patterns/ gives a good overview of things to explore in Flask. Edit: I elaborated a bit more. Please note that I'm not advocating anything, just giving my opinion on their documentation.