About the team SumUp’s Point-of-Sale (POS) solution empowers cafes, shops, bars, hair salons, and other businesses to operate efficiently and grow. It offers a wide range of features, including product catalogs, inventory management, business analytics, compliance support, and loyalty tools. Our Fiscalization team will accelerate making the following countries fiscally compliant: Italy, Sweden, Norway, Belgium, Austria, and many other European countries. They will also start building the path for integrating with third parties and fiscalizing receipts. As a Senior Backend Engineer, you’ll collaborate with a dynamic, cross-functional team of Product Managers, Product Designers, Engineering Managers, and fellow engineers. About the role You will be working on secure backend systems to ensure our SumUp’s Point of Sale (POS) products are compliant in the different countries in our roadmap. Furthermore, you will work with the Fiscalization squad to understand the challenge in each market to design a unique solution to delivery. You’re a developer who values user-centric design, precision, and seamless collaboration. You bring structure to communication and thrive in a cross-functional environment.  This will be B2B role for our team in Warsaw. What you’ll do * Build and maintain fiscal compliance solutions to enable SumUp's expansion across Italy, Sweden, Norway, Belgium, Austria, and other European markets. * Develop integrations with third-party services for receipt fiscalization and regulatory reporting systems. * Navigate SumUp's complex POS ecosystem and master fiscalization frameworks across multiple jurisdictions. * Collaborate with distributed squad members and stakeholders across 5+ cities in a hybrid environment. You’ll thrive in this role if: * You have 5+ years experience in backend engineering with Java and/or Kotlin. * You have a strong understanding of fundamental system architecture, design principles, data modeling, and API design. * You have a strong experience with distributed and fault-tolerant systems. * You have user-level experience working with AWS and Kubernetes. * You have good knowledge of Kafka, Postgres, & CQRS. WHY YOU SHOULD JOIN SUMUP (WARSAW) 🇵🇱 🌈 Commitment to Diversity and Inclusion: be part of a workplace that values and promotes diversity, fostering an inclusive environment where everyone's perspectives are respected and embraced  🚀 Enrolment onto our VSOP program: you will own a stake in SumUp’s future success  🚴 Fitness support: work out on-site at our gym or explore the city using the Multisport Card, subsidised by SumUp for access to sports facilities across Warsaw  🩺 Commitment to well-being: access health insurance coverage for you and your family, plus life insurance to further protect your peace of mind  💰 PPK (Employee Capital Plan): grow your savings with joint contributions from SumUp and the State.  🏖️ Generous time off: enjoy 26 days of paid leave plus public holidays and special leave days 🌴 Break4me: 1-month sabbatical after 3 years of service  🔗 Referral Bonus: earn additional rewards by referring talented individuals to join the SumUp team   Salary range: 18 850 - 29 660 PLN per month Job Application Tip We recognise that candidates feel they need to meet 100% of the job criteria in order to apply for a job. Please note that this is only a guide. If you don’t tick every box, it’s ok too because it means you have room to learn and develop your career at SumUp.