What most system design articles skip is the part where you explain why the boring choice was the right one
I built a platform that runs social media giveaway events, a gift card marketplace, and telecom gift vending — all in one system, all sharing the same PostgreSQL database and Redis instance, all running in production on infrastructure that costs €27 a month.
This article is not about the product. It is about the seven architectural decisions I made while building the backend, why I made them, and what the actual capacity ceiling looks like before anything needs to change.
The full architecture document (20 sections, every design decision documented) is linked at the end. This is the version you can read in ten minutes.
1. Three services, not ten — and not one
