Flask-AppBuilder is described as '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' and is an app in the Development category. There are three alternatives to Flask-AppBuilder for Online / Web-based, Self-Hosted solutions, SaaS, Windows and Linux. The best alternative is WaveMaker. It's not free, so if you're looking for a free alternative, you could try nuBuilder or Xataface.
WaveMaker is an award winning Low Code Platform that helps create enterprise grade web and mobile apps. With over 10 years of market presence, thousands of developers use it to create applications 67% faster.
nuBuilder is a web-based database application platform. nuBuilder can be used to make a variety of applications such as accounting or CRM systems. Any system that requires a database to store information.
Xataface is a flexible and shapable skin that sits on top of MySQL, making it accessible to every-day users. It automatically generates the appropriate forms, lists, and menus for a user to interact with the database without having to know any SQL.