Senior Backend Engineer - Cards

Overview

SumUp builds simple, affordable financial tools that help small businesses get paid, manage their money, and grow. Beyond payments, we offer a number of financial products - including business banking, card products, lending, and invoicing — giving merchants everything they need to manage their payments and finances in one place. The Cards squad is a core part of that, owning the systems that power card issuing, lifecycle management, and transaction processing for merchants across Europe. We handle millions of card transactions every day, and we're now scaling those systems to support new product capabilities while laying the foundations for a more global, resilient platform. That's why we're growing the team and looking for a seasoned backend engineer who can take real ownership of complex, high-impact work. If you want to build systems that genuinely matter to small businesses and you're excited by the technical depth that comes with high-throughput, distributed architecture, this is the role for you. 🎥 Join us in our Sofia Team - get a feel for our Sofia office here . What you'll do Own and lead the end-to-end delivery of backend services within the Cards EU domain, including observability, testing, and production support Contribute to the technical roadmap by participating in architectural discussions and proposing solutions for complex, distributed systems challenges Raise well-scoped pull requests, conduct thorough code reviews, and help maintain high standards of code quality and test coverage across the team Collaborate closely with engineers in adjacent squads and with the product manager to shape and refine the squad backlog Participate in incident reviews and the on-call rotation, taking accountability for the reliability of the services you build Apply and champion AI tooling to accelerate engineering workflows, and help raise the team's overall AI literacy You'll be great for this role if… Solid, hands-on experience deliveri

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