Backend Engineer - POS

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. As a Backend Engineer in the Orders & Sales or Catalog Platform team, you will build the engine powering core infrastructure for over 4 million businesses worldwide. Whether you are architecting global sales APIs or scaling item management systems, your work is central to the SumUp ecosystem. The Orders & Sales team builds high-performance APIs and receipt engines that unify transaction and sales data, utilizing an AI-native mindset and extreme collaboration. Meanwhile, the Catalog Platform team owns the backend for item management, variants, categories, and taxes, focusing on high-stakes reliability and core POS infrastructure scaling. What you’ll do Develop and evolve high-performance backend services and APIs using Kotlin and Spring Boot . Design and maintain robust data schemas and event-driven integrations (Kafka) to handle complex transaction and catalog data at scale. Write clean, well-tested, production-grade code and contribute meaningfully to code reviews and team rituals. Collaborate with mobile and product teams to ship end-to-end features with a focus on performance and data consistency. Engage in daily pair programming to solve complex concurrency challenges and maintain high architectural standards. Take full ownership of the development lifecycle, including managing CI/CD pipelines and monitoring service health in production. Actively use and experiment with AI coding agents to automate repetitive tasks and increase shipping velocity. Refactor and migrate mission-critical domain logic to centralize and simplify the "Sales" and "Catalog" experiences across the ecosystem. You’ll be great for this role if You have 3+ years of experience in backend engineering with the JVM stack (preferably Kotlin and Spring Boot ). You have a solid understanding of software design patterns, data modeling, and fundamental system architecture principles. You are comfortable working with Kafka , Postgres , and AWS in a production environment at scale. You enjoy and actively seek out collaboration and daily pair programming as a primary way of working. You are an "AI-native" engineer, open to using agents and tools to optimize your coding process. You have experience with, or a strong interest in, distributed and fault-tolerant systems. You are a fast learner who values quality, detail, and effective time management. You are fluent in English and can communicate clearly with both technical and non-technical stakeholders. Nice to have Experience with Kubernetes and cloud-native observability/monitoring tools. Knowledge of different programming paradigms (Functional vs. OOP). Familiarity with high-scale applications involving many concurrent processes. A desire to share knowledge with the wider engineering community. Why you should join SumUp 🌎 Opportunity to work with SumUppers globally on large-scale fintech products used by millions of businesses worldwide, from our Berlin office. This involves an office-first setup 🌈 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 Virtual Stock Option programme: you will own a stake in SumUp’s future success 📚 A dedicated annual L&D budget of €2000 for your individual development, which you can be used to attend conferences and/or advancing your career through further education 💶 A corporate pension scheme where we match up to 20% of your contributions 🏖️ Generous time off: enjoy 28 days of paid leave plus public holidays and special leave days 🚵🏾‍♂️ Numerous other benefits such as Urban Sports Club subsidy, Kita placement assistance, subsidised office lunch...