Senior Java Developer

We are looking for Senior Java Developers to join a long-term payments technology programme focused on terminal management systems supporting more than 300,000 payment terminals across multiple hardware vendors. The role combines backend development, integrations, and system modernisation within a complex enterprise payments environment.

This is a hands-on Java role working across both legacy and modern architectures, including migration from Wild. Fly-based systems to Spring Boot microservices, with strong focus on integrations, distributed systems, and payment infrastructure reliability.

Responsibilities

• Design and implement IT solutions based on analytical and technical documentation
• Review analytical documentation and translate it into technical implementation
• Create and maintain technical documentation
• Support technical upgrade and modernisation of the existing system
• Work with legacy code and contribute to gradual system migration
• Conduct regular application scans and remove vulnerabilities
• Build and maintain integrations with internal and external systems
• Work with distributed transactions, queues, caching, and database integrations Requirements
• Very good knowledge of Java 8+ and object oriented programming
• Practical experience with Spring, Spring Boot, Hibernate/JPA, and JEE
• Experience designing, implementing, documenting, and testing application components independently
• Practical knowledge of RabbitMQ or other message queue systems
• Good knowledge of Maven, Git, GitLab, GitLab CI/CD, Jenkins, Nexus, Jira
• Knowledge of relational databases, especially Oracle
• Practical experience with REST API design
• Experience with system integrations and distributed systems
• Experience with application servers such as JBoss / Wild. Fly
• Knowledge of scanning tools such as Fortify or Sonatype
• English B2
• Full availability in the Polish time zone
• Ability to work 4 days per week from the Warsaw office Nice to have
• Experience in payments, acquiring, terminal management, or financial services
• Experience with SOAP, RMI, database links, or direct database integrations
• Experience with Hazelcast or distributed caching
• Experience with distributed transaction patterns such as two phase commit or Saga
• Experience working with legacy systems and migration programmes
• Experience with GWT / GWTExt Benefits Solid, competitive salary Work in a multinational environment on international projects Comprehensive healthcare Long-term B2B contract with a stable project pipeline Flexible hybrid model (4 days/ week on-site in Warsaw)