Senior Java Software Engineer

Senior Java Software Engineer – AI-Driven Modernisation Miejsce pracy: Toruń Technologies we use Expected Java AI LLM GitHub Copilot Claude Code About the project We’re building a next-generation technology team focused on modernising critical financial services through AI-first engineering. You’ll play a key role in transforming complex legacy systems into modern, scalable, and intelligent solutions. You’ll work hands-on with the latest AI tools to accelerate development, improve code quality, and deliver measurable impact across the organization. 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. Your responsibilities Modernizing legacy systems using AI to analyze, refactor, and optimize existing codebases Implementing modern architecture patterns, including strangler fig and microservices migration approaches Delivering production-ready services with robust testing, clear documentation, and multi-instance deployment support Using AI tools throughout the SDLC to boost productivity and ensure faster delivery cycles Collaborating with cross-functional teams to ensure smooth service transition and ownership handover Demonstrating measurable improvements in performance, reliability, and API efficiency Our requirements Minimum 7 years of professional experience in Java programming Experience with legacy system refactoring or service modernization projects Hands-on experience with AI-powered development tools (e.g., GitHub Copilot, Claude Code, or similar LLMs) Solid understanding of CI/CD, automated testing, and cloud-native architectures Ability to design scalable, secure, and maintainable software solutions Willingness to travel to Krakow for short business delegations as needed Excellent command of English, both written and spoken, enabling effective communication in an international environment Residing in Poland required This is how we work on a project Continuous Deployment Continuous Integration 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 – you can change them thanks to Job Changer application 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 Recruitment stages Send your CV Talk to us about your expectations Learn more about our projects and choose the best Start your adventure with Sii Sii Sp. z o.o. Sii is the leading technology consulting, digital transformation, engineering, and business services vendor in Poland. We already employ more than 7 300 professionals and implement projects in a variety of industries for clients from many countries around the world. The Great Place to Work title, won 10 times in a row, proves that at Sii, we create a friendly work environment. 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.