01Where digital payments meet physical operations
Dennypay, UAB is a Vilnius-based fintech platform serving merchants whose checkout extends beyond a conventional till. Its payment solutions cover self-service car washes, vending and coffee machines, parking, ticketed access, hotels and restaurants.
The engineering challenge is the handoff: a payment is authorized online, a merchant needs a reliable transaction record, and a physical service must respond at the right moment. The mobile app brings those operational touchpoints into one merchant interface.
02My contribution: FlutterFlow prototype to custom Flutter
I worked on the merchant mobile ecosystem, starting with FlutterFlow to validate navigation, transaction views and operational flows, then moving into a custom Flutter and Dart codebase. That transition supported more control over state, background work and native device integrations.
The goal was to retain the speed of the validated product while giving payment workflows and device interactions clearer application boundaries. The resulting scope connects the merchant experience with Adyen services and AWS-backed payment events.
03Adyen payment workflows for self-service and hospitality
The payment integration scope covered contactless terminal orchestration, payment links, card pre-authorizations, delayed capture and OTA virtual card processing. These are different transaction lifecycles: a hotel deposit is not the same event as a completed vending purchase.
Merchant screens surface transaction status and operational context so teams can distinguish authorization, capture and settlement activity. Reconciliation, multi-location visibility and recurring-payment flows formed part of the delivery scope.
04AWS webhooks and connected hardware
AWS backend services and webhook listeners connect payment callbacks with downstream hardware workflows. Relevant touchpoints include ANPR parking systems, barrier gates, QR access validation and vending activation.
The architecture separates a payment event from the action it enables. That distinction matters when a terminal, controller or network connection is temporarily unavailable: the merchant needs a traceable payment state as well as a clear record of the requested physical action.
05A merchant dashboard built around operations
The unified mobile dashboard brings transaction monitoring, reconciliation and multi-location revenue views together across unattended terminals and POS endpoints. The application architecture supports the native integrations and background processing needed around those flows.
The result is a merchant experience organized around the full transaction lifecycle: monitor a payment, understand its status and connect it with the physical service the customer requested.
