Senior Backend Engineer - Money Transfers

Responsibilities

• Build and maintain backend services that sit at the heart of SumUp's transfer infrastructure, taking end-to-end ownership from development through to observability, testing and production support
• Contribute to the migration from market-specific services toward a unified global transfer platform, working across a mix of active services and legacy systems being decomposed
• Raise well-scoped pull requests, conduct thorough code reviews, and help maintain high standards of code quality and test coverage across the team
• Participate in incident reviews and the on-call rotation, taking accountability for the reliability of the services you build
• Contribute to the technical roadmap by participating in architectural discussions and proposing solutions for complex, distributed systems challenges
• Apply AI tooling to accelerate your own engineering workflows and contribute to raising the team's overall AI literacy
• You'll be great for this role if...
• Solid experience as a Backend Software Engineer in modern languages (e.g. Kotlin, Go, Java, etc.). Kotlin is the team's primary language and we also work with Java, Golang, and Elixir.
• Solid understanding of distributed systems and event-driven architecture. Experience with async processing and messaging tools like Kafka (or similar).
• Experience working with microservice architectures, including Spring Boot and event-driven patterns, alongside solid knowledge of relational databases and API design
• Comfortable working in high-throughput, regulated environments where reliability matters. Defensive coding and attention to edge cases are part of the job
• Clear communicator in written and spoken English, with a collaborative approach to working across global teams
• Curious about the product impact, not just the code. Comfortable thinking about how backend decisions affect the end user experience.
• Why you should join SumUp
• 🌍 Opportunity to work with SumUppers globally on large-scale fintech products used by millions of businesses worldwide, from our modern Sofia 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 and 10 paid days of educational leave which can be used to attend conferences and/or advance your career through further education
• 🏖 Generous time off: 25 days of paid leave, plus one extra day per year of service (up to 35), along with public holidays and special leave options
• 🏥 Peace of mind: additional health insurance and life insurance
• 💪 Stay active: on-site yoga and a co-sponsored Multisport card offering access to hundreds of sports facilities
• 🍽 Meal support: benefit from a tax-free food voucher program plus flexibility via our Re:Benefits platform
• 🚌 Easy commute: free shuttle buses connecting directly to Joliot-Curie metro station
• 🌴 Break4me: 1-month sabbatical after 3 years of service
• 🔗 Referral Bonus: earn additional rewards by referring talented individuals to join the SumUp team
• About SumUp
• Be empowered to do more that matters.
• At SumUp, we're on a mission to empower small businesses across the globe by providing simple and affordable to

Benefits

Additional Information

SumUp builds simple, affordable financial tools that help over 4 million small businesses across 37 markets get paid, manage their money, and grow. Beyond card payments, we offer a full suite of financial products - business banking, lending, invoicing, and money transfers - giving merchants everything they need in one place. We're a global fintech with over 3,000 people across 20+ offices, and Sofia has been one of our most important engineering hubs since the very beginning. Our Transfers Excellence squad sits within SumUp's Global Bank , and owns the core services that power how merchants and consumers move money. E.g. IBAN-based transfers, money in and out, and peer-to-peer payments via the SumUp consumer app. With the high volume transfers per hour across our European markets. That means reliability isn't a nice-to-have - it's the baseline for us. Right now, the team is replacing a set of market-specific implementations with a single, unified global transfer platform that will serve Europe, the UK, Brazil, Chile, and eventually the US and Canada. Join our team and contribute directly to platform-level architecture that will shape how SumUp moves money at scale - work that directly impacts millions of small businesses every day. Our tech stack includes Kotlin, Java, Go, a bit of Elixir, AWS, Kafka, PostgreSQL, and Kubernetes, supported by a strong observability toolchain with Prometheus, Grafana, and Honeycomb. We also actively use AI‑assisted development tools such as Cursor, GitHub Copilot, and others. 🎥 Get a feel for life in our Sofia office .

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