I've been approached by a business consultant for programming a website + web application for his client, which is a logistics company. The web application will have a tracking system for tracking their GPS enabled fleet (400 tricks).

Kindly advise me which scaleable stack can I use for the back-end. I'm planning to use React for the front-end.

And by back-end, I also include the database. I'm considering PostgreSQL as the database system.