Backend Engineer (Junior-Mid) - Java, Payments Tribe at Sumup

At SumUp, we build the financial tools that empower small businesses around the world. Our Payments Tribe is at the heart of that mission - powering billions of transactions across 36+ markets every year. Our Sofia office is home to our Payouts Squad, a team working on one of the most business-critical components of our payments infrastructure - the platform through which all SumUp payouts are processed. The Role We're looking for a Junior/Mid level Backend Engineer (Java) to join our Payouts Squad in Sofia. You'll be part of a team building a brand-new, scalable payouts platform - transitioning from a legacy system to a modern event-driven microservices architecture while also supporting and maintaining the existing platform. This is a high-impact role on an experienced team. The platform you'll help build processes real money across multiple markets, making quality, reliability, and sound engineering judgement essential from day one. You'll work closely with senior engineers and benefit from strong mentorship in a complex, business-critical domain. What You'll Do • Contribute to building a new event-driven microservices platform for payouts, designed to scale across multiple markets • Support and maintain the existing legacy payouts system while the new platform is being developed • Build and consume RESTful APIs and work with both SQL and NoSQL databases • Participate in code reviews and help ensure high engineering standards across the team • Add observability and debugging support to existing payment processing flows • Work closely with senior engineers to understand the domain and contribute to design decisions You'll Be Great for This Role If You • Have hands-on experience with Java - from work, studies, or personal projects • Have backend programming experience and a solid understanding of software design principles • Are comfortable building and consuming RESTful APIs • Have familiarity with SQL and/or NoSQL databases (we work with CockroachDB, PostgreSQL, and Kafka) • Are eager to deepen your understanding of system architecture, data modelling, and distributed systems • Are open to feedback, not afraid to voice your ideas backed by data, and enjoy pairing with teammates • Are comfortable (or curious) working across multiple tech stacks — including Go and Kafka Nice to Have • Experience with AWS, Kubernetes, or Docker • Exposure to Ruby or another functional/scripting programming language • Familiarity with event-driven architectures or message brokers like Kafka • Background or interest in the fintech / payments industry What We Offer • Work on a business-critical payments platform with real impact across multiple global markets • Strong mentorship — a small, experienced team with senior engineers invested in your growth • Modern tech stack: Java, Kafka, PostgreSQL, AWS, Kubernetes • 🏢 Sofia office-based role in a collaborative, international environment • Access a €2,000 annual L&D budget to attend conferences or advance your career through education. • Enjoy 25 days of paid leave (increasing with tenure), plus paid vacations for special occasions and a 1-month sabbatical every 3 years. • Benefit from extra perks like health and life insurance, co-sponsored Multisport cards, childbirth/adoption bonuses, discounts, a referral program, monthly food vouchers, flexible benefits, and more. Please note: This role requires the right to work in Bulgaria. We are currently not able to support visa applications or relocation for this position at this time. About us: SumUp is a leading financial technology company, founded in 2012 with the goal of empowering small businesses around the globe. We’re the financial partner of choice for more than 4 million merchants in over 35 markets. We collectively build, plan and fine-tune the technology that drives SumUp and empowers small businesses around the world. We believe in the everyday hero. Those who have the courage to follow their passion and who have the strength and determination to realise their dreams. Small business owners are at the heart of all we do, so we're creating powerful, easy-to-use financial solutions to help them run their business. With a founder's mentality and a 'team-first attitude' our diverse teams across Europe, South America, and the United States work together to ensure that small business owners can be successful doing what they love. SumUp is an Equal Employment Opportunity employer that proudly pursues and hires a diverse workforce. SumUp does not make hiring or employment decisions on the basis of race, colour, religion or religious belief, ethnic or national origin, nationality, sex, gender, gender identity, sexual orientation, disability, age or any other basis protected by applicable laws or prohibited by Company policy. SumUp also strives for a healthy and safe workplace and strictly prohibits harassment of any kind. 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.