Summary

Senior back-end engineer to own and re-architect the payment-terminal platform powering restaurant kiosks, currently spanning 40+ integrations across card-present terminals, processors, and cash automation. You will design a modular, pluggable SDK enabling internal and external developers to build integrations against a stable contract, implement new integrations from wire-level protocols (TLV, BMP, APDU, BCD/LLVAR) up through high-level APIs, and establish platform-wide patterns for payment correctness (idempotency, transaction recovery, reconciliation). Role requires 6+ years back-end engineering with strong Java, Spring, OOP, and distributed-systems design; hands-on work with serial (RS-232/USB-serial via jssc) and USB (usb4java) transports, REST/SOAP/webhook integrations, and PCI-DSS compliance patterns.