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Expect system design for high-throughput payment APIs, debugging concurrency and data consistency, and behavioral examples of shipping backend changes under reliability constraints. Practice explaining trade-offs in service boundaries, idempotency, and observability.
Strong fit if you enjoy senior backend ownership in fintech (payments, merchants, multi-market scale) and prefer on-site/hybrid Berlin work over remote. Thin public culture signals in the provided data—validate team stack and on-call norms in interview.
As a Senior Backend Engineer at SumUp in Berlin, a typical day centers on payment and merchant systems: designing and shipping APIs/services, reviewing code, hardening reliability around card and online payment flows, and coordinating with product and platform teams on latency, correctness, and scale.
Strengthen backend fundamentals (APIs, data stores, concurrency) and payments-relevant reliability. Free resources:
The listing marks remote as no; plan for Berlin-based work unless SumUp confirms otherwise.
Merchant-focused fintech: card readers, online payments, and related banking/investing features across many markets.
No paid cert is required from the provided list; free paths like freeCodeCamp, Saylor CS, CS50, and Microsoft Learn cover core developer skills.
Website: sumup.com
SumUp is a British financial technology company headquartered in London. SumUp’s primary product is an EMV card reader and a number of online payment and bank account system for merchants and businesses.
Public cache only — not an employee review.
Senior Backend Engineer - Cards at SumUp in Berlin, Germany (Full Time, No Remote) About This Position At SumUp, we build simple, affordable financial tools to help small businesses thrive. Our Cards squad is crucial for this mission, owning the systems that power card issuing, lifecycle management, and transaction processing across Europe. We're scaling our systems to support new product capabilities while laying a foundation for global resilience. This role requires a seasoned backend engineer who can take ownership of complex, high-impact work. Day-to-Day Responsibilities Owning and leading the end-to-end delivery of backend services within the Cards EU domain, including observability, testing, and production support Contributing to the technical roadmap by participating in architectural discussions and proposing solutions for complex, distributed systems challenges Raising well-scoped pull requests, conducting thorough code reviews, and helping maintain high standards of code quality and test coverage across the team Collaborating closely with engineers in adjacent squads and with the product manager to shape and refine the squad backlog Participating in incident reviews and the on-call rotation, taking accountability for the reliability of the services you build Applying and championing AI tooling to accelerate development processes Skills & Qualifications Experience with backend systems architecture, particularly in high-throughput, distributed environments Proficiency in at least one modern programming language (e.g., Go, Rust, Python) A strong understanding of observability and monitoring tools for complex systems Ability to write clean, maintainable code with a focus on test coverage Experience with version control systems like Git Strong problem-solving skills and the ability to work in a fast-paced environment A passion for building impactful systems that support small businesses Why Join SumUp Joining SumUp means being part of a dynamic, mission-driven team. We offer competitive salaries and benefits, along with opportunities to shape the future of financial tools for small businesses. Our Berlin office provides a vibrant work environment that encourages innovation and collaboration. Apply Today To apply, complete your application directly on this page, or you'll be redirected to the employer's application platform to finish submitting there.
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