1. Tech stack has to be decided based on functional requirements (real-time chat, less-write but read-intensive etc) and non-functional requirements (concurrent

1. Tech stack has to be decided based on functional requirements (real-time chat, less-write but read-intensive etc) and non-functional requirements (concurrent connections to support, regulatory compliance requirements etc). 2. Any serious business system (not just one app) will have multiple tech stack. 3. In the long term tech stack has to change depending on the changing business needs. Assuming a whole lot about above 3 points, choice could be postgres, python, react, aws. Purely because they are battle tested. Any discussions about their merits are moot without knowing requirements.