Flask-AppBuilder

Simple and rapid application development framework, built on top of Flask. includes detailed security, auto CRUD generation for your models, google charts and much more. Demo (login with guest/welcome) - http://flaskappbuilder.pythonanywhere.com/. Maintained by dpgaspar on GitHub, where it has earned 4,955 stars from the community.

It's actively developed around web, flask, crud, and is a solid reference for anyone building with these tools.