What technology I should use to develop web page group chat app and how do I handle the chat data?

Deciding on the technology for chat app development is a subjective matter that varies based on the developer to the developer as well as the actual requirement for the development.

Below technology, the stack is preferred by a well-experienced web & Mobile application development agency who has also written an article on How to Develop a Chat App

Hope the above picture clears all the queries.