When I joined NFCtron we were a small team — 3 engineers, including the technical co-founder — so we did everything ourselves. This included:
The team grew to 10–15 while I was there, and NFCtron became the leading festival payment provider in the Czech Republic.
My core focus was a platform for event organizers called NFCtron Plus. The main goal was to give all the merchants and event organizers real-time access to their data. The secondary goal was to drastically simplify event setup — the product catalog and basically every setting of an event — which previously had to be done manually by support people or developers.
I also worked on the customer-facing app for buying tickets and managing credit deposits. This included multiple MVPs and a lot of user testing.
Underneath all of it we were rewriting the payment system (Node.js, with a Flutter mobile app), including a long migration from a non-relational to a relational database that required a gradual rewrite of much of the application. The hardest and most interesting part was the NFC tokens themselves: we reworked the token's physical-layer data model to prevent double-spending in near real-time. Festivals are intermittent-connectivity by nature, so the payment path had to stay correct even when offline. At our scale — ~1B CZK/year processed, and peak events like Rock for People at ~40k concurrent attendees and ~1k seller devices — that meant designing for zero downtime and zero transaction errors, rather than catching errors after the fact.