Java developer in payment platforms

We are looking for a Java Developer for a B2B contract opportunity, operating in a hybrid model based in Warsaw, to join a specialist engineering team delivering critical changes across complex payment platforms. Role overview: You will work within a small, experienced delivery pod, focusing on analysing and enhancing legacy systems in line with evolving financial messaging requirements. This role requires strong technical depth, the ability to navigate and refactor complex codebases, and confidence working in time-sensitive delivery environments.

• Strong hands-on experience with Java and the Spring ecosystem (including dependency injection, data access, and security)
• Proven experience designing and developing RESTful APIs across full stack applications
• Solid knowledge of relational databases (e.g. DB2) and NoSQL databases (e.g. MongoDB), including schema and document modelling
• Experience working with event-driven and distributed systems, including streaming platforms (e.g. Kafka), producers/consumers, and stateful processing
• Familiarity with messaging technologies (e.g. IBM MQ, JMS) and asynchronous communication patterns
• Experience with build and dependency management tools (e.g. Maven) and multi-module project structures
• Practical knowledge of containerisation (e.g. Docker) and modern development environments
• Experience with version control (Git) and CI/CD pipelines (preferably GitLab CI)
• Exposure to infrastructure as code and environment provisioning
• Understanding of financial systems, payments, or transaction-heavy platforms, including familiarity with financial messaging standards (e.g. ISO 20022, SWIFT)
• Scripting capability (e.g. Python) to support automation or data processing
• Proven ability to analyse, reverse engineer, and enhance legacy systems with limited documentation
• Strong problem-solving capability and attention to detail
• Confidence working in complex, fast-paced environments with evolving priorities
• Ability to balance delivery speed with code quality and maintainability
• Effective communication skills and a collaborative mindset within distributed teams
• Ownership, accountability, and a proactive approach to improving systems and processes

• B2B contract opportunity
• operating in a hybrid model based in Warsaw