Java Backend Developer

Job Description We are looking for a Java Backend Developer to join a production-critical backend platform within the payments domain. The role focuses on building and maintaining high-performance backend services in a regulated, high-scale environment, supporting transaction processing, settlements, financial reporting, and integrations with internal and external systems. Strong hands-on Java experience and comfort working with mature, mission-critical systems are essential. Responsibilities Design and develop backend services using Java 17+ Build scalable components supporting transaction data, settlements, and reporting Integrate backend services with relational databases and internal financial systems Develop secure REST APIs aligned with compliance and security standards Collaborate closely with product owners, analysts, architects, and QA teams Optimise system performance, reliability, and data processing efficiency Participate in code reviews, testing, and continuous improvement activities Support platform modernisation and resolve production issues Contribute to clean code practices and long-term platform scalability Requirements 3–5 years of commercial Java backend experience Strong knowledge of Java 17+ and modern backend frameworks Hands-on experience with relational databases (SQL; Oracle / PL/SQL preferred) Experience working with microservices and distributed systems Solid understanding of REST API design and system integrations Experience working in Agile delivery teams Good communication skills and ability to work in international environments Nice to have Experience in fintech, payments, banking, or other regulated domains Exposure to CI/CD pipelines, DevOps practices, or containerised environments Experience with messaging or event-driven architectures Background in high-volume or real-time systems Benefits Solid, competitive salary Work in a multinational environment on international projects Comprehensive healthcare Long-term B2B contract with a stable project pipeline Hybrid working model (remote with 1 day per week in the Warsaw office)