The challenge
A three-day festival cannot wait for a network. Card terminals stall the moment connectivity drops at a gate, and a queue at the bar is revenue walking away. The operator needed a closed-loop payment system that kept taking money when the signal did not — and reconciled to the cent once it came back.
Eighty thousand attendees, hundreds of points of sale, and one hard rule: a tap should clear in well under a second, every time, online or off.
What we built
We designed an offline-tolerant terminal around an NFC wristband as the wallet. Each tap is signed locally and queued; terminals settle opportunistically whenever they reach the network, and the ledger resolves double-spends deterministically. Top-up happens at kiosks, online, or at staffed booths — all writing to the same balance.
The hardware and firmware were ours end to end, from the validator board to the cloud dashboard the operator watched live. Wristbands, kiosks, and access control were designed to run as one system rather than three integrations bolted together on site.
We treat infrastructure as a product — instrumented, documented, and built to be operated. Not handed over and forgotten.Protocore · Engineering principles
The outcome
Over three days the system cleared €2.4M with a median tap-to-confirm of 120 milliseconds and zero settlement disputes. Staff topped up and refunded from the same terminals, and the operator closed the books the morning after the gates shut.