Sii ensures that all employment-related decisions are made solely on the basis of qualifications and competencies. We are committed to equal treatment of all individuals, regardless of any protected characteristics, and promoting a diverse and inclusive work environment.We are looking for a mid-level Java Developer to join our team. You will work on a modern backend built in Java and Spring Boot, expose RESTful APIs consumed by the frontend, and integrate with multiple external systems. This is a hands-on role where you will take part in building new features, improving system architecture, and ensuring code quality.Your tasks Develop, maintain, and optimize backend services built with Java and Spring Boot Design and implement REST APIs used by the frontend and external partners Integrate with external APIs and ensure reliable data exchange Write clean, testable, and maintainable code (unit & integration tests with Spock/JUnit) Work with PostgreSQL and use Flyway for database migrations Participate in code reviews and contribute to continuous improvement Collaborate with cross-functional teams in an Agile environment Use Git for version control and GitHub Actions for CI processes Requirements Minimum 4 years of commercial experience in Java development Strong knowledge of Spring Boot and building REST-based applications Proficiency with SQL and relational databases (PostgreSQL) Experience with unit and integration testing (Spock/JUnit) Solid experience working with Git Practical understanding of API integrations Strong analytical and problem-solving abilities Good command of both English and Polish (written and spoken) Residing in Poland required Nice-to-have requirements Experience with AWS or other cloud services Familiarity with Docker or containerization practices Knowledge of CI/CD pipelines (e.g., GitHub Actions) Understanding of software architecture and design patterns Previous use of Flyway for schema versioning What we offer  Great Place to Work since 2015 - it’s thanks to feedback from our workers that we get this special title and constantly implement new ideas  Employment stability - revenue of PLN 2.1BN, no debts, since 2006 on the market  We share the profit with Workers - over PLN 76M has already been allocated for this aim since 2022  Attractive benefits package - private healthcare, benefits cafeteria platform, car discounts and more  Comfortable workplace – class A offices or remote work  Dozens of fascinating projects for prestigious brands from all over the world  PLN 1 000 000 per year for your ideas - with this amount, we support the passions and voluntary actions of our workers  Investment in your growth – meetups, webinars, training platform and technology blog – you choose  Fantastic atmosphere created by all Sii Power People  Join the Sii team – develop your skills, gain experience, and build your career!