Mid/Senior Backend Engineer (Java)

Senior Backend Engineer (Java) Payments Orchestration | Greenfield Gaming Platform CONTRACT B2B LOCATION Remote / Poland WORKSHOPS Kraków START ASAP / agreed date B2B RATE 160–200 PLN/h + VAT Final rate depends on seniority, payments experience and technical fit. The Mission West Code is building a new engineering team for a greenfield international gaming platform. The Payments team will own payment orchestration and integrations with external payment providers. You will work on backend services where reliability, transaction consistency and failure handling matter as much as clean code. This is a hands-on role with real influence on technical design and implementation from the beginning. What You’ll Build payment orchestration services with Java 21+ and Spring Boot 3 provider / PSP integrations and a consistent integration layer transaction flows such as deposits, withdrawals, refunds, reversals and status handling routing, retry, timeout and fallback mechanisms idempotency and duplicate-event protection asynchronous callbacks / webhooks and event-driven flows reconciliation and transaction-state consistency high-volume, highly available services with strong observability Must Have 4+ years of backend engineering experience strong Java and Spring Boot experience with microservices and distributed systems Kafka or a similar messaging platform REST APIs and external system integrations SQL / PostgreSQL or similar relational database experience Docker and CI/CD experience working with production systems good English and ability to work independently Strong Advantage hands-on experience with payments, payment gateways, PSPs or fintech payment orchestration, provider adapters or routing logic idempotency, retries, callbacks, reconciliation or transaction state machines wallets, high-volume transactional systems, e-commerce or marketplaces iGaming, sportsbook or online casino Kubernetes and AWS Kotlin or Scala OpenTelemetry, Prometheus, Grafana or similar observability tooling Engineering Environment Java 21+ · Spring Boot 3 · Kafka · PostgreSQL · Docker · Kubernetes · AWS · REST APIs · OpenTelemetry · CI/CD Working Model B2B cooperation remote work from Poland initial workshops in Kraków and follow-up onsite sessions approximately once per quarter international team with English used on the project greenfield delivery with direct access to senior technical leadership Why West Code At West Code, we build engineering teams around ownership and strong technical delivery, not just individual roles. You’ll join a real greenfield platform build, influence technical decisions and work on problems where payments, reliability and distributed-system design genuinely matter. Our delivery environment also uses AI-assisted engineering workflows to support code quality, security, requirements context and knowledge transfer. Sounds like your kind of project? Apply and let’s talk.