Mid/Senior Backend Engineer (Java)

Quick Facts

• Role: Mid/Senior Backend Engineer (Java)

• Focus: Payments orchestration and external payment provider integrations

• Work model: Remote from Poland; initial workshops in Kraków with periodic onsite sessions

• Start: ASAP or agreed date

Description

You will help build a greenfield international gaming platform by owning payment orchestration backend services. The role emphasizes reliability, transaction consistency, failure handling, clean code, and hands-on design and implementation. You’ll integrate with external payment providers, implement idempotency/duplicate-event protection, and build event-driven callbacks with strong observability.

Responsibilities

• Build payment orchestration services using Java 21+ and Spring Boot 3

• Create a consistent integration layer for provider/PSP integrations

• Implement transaction flows: deposits, withdrawals, refunds, reversals, and status handling

• Develop routing, retry, timeout, and fallback mechanisms

• Ensure idempotency and duplicate-event protection

• Handle asynchronous callbacks/webhooks and event-driven flows

• Support reconciliation and transaction-state consistency

• Deliver high-volume, highly available services with observability

Requirements

• 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 databases)

• Docker and CI/CD

• Experience working with production systems

• Good English and ability to work independently

Benefits

• Greenfield delivery with direct influence on technical design from the beginning

• Hands-on ownership in a payments-focused team

• International team using English on the project

• AI-assisted engineering workflows to support code quality, security, requirements context, and knowledge transfer