We built our app using FASTAPI for the backend server and MongoDB for the backend database server, so this is for data persistance.
FASTAPI is a modern and fast web framework for building APIs, created by Sebastien Ramirez,
it uses ASGI which is the interface between your app and the server and the response time is lightening fast
and this is one of the big advantages of having ASGI server implementaion on your side.
Also, one if its big features that it supports coroutines and concurency without the need to import the ASYNCIO module in Python,
and in a way it's faster than Express which is NodeJs framework ( and Express is E in the MEAN and MERN stacks ).
FASTAPI also has interactive API documentation, so it helps you testing the different HTTP requests like get post,
put and delete visually using Open API which is itself based on JSON schema.
Future scope is to make a frontend for the api using React and making it a fullstack (FARM stack) website.