Senior Backend Engineer (Kotlin) - Cards

SumUp·Sofia, Bulgaria·Posted 9 October 2026

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About the role

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 owns the systems that power card issuing, and transaction processing for merchants across Europe, handling millions of transactions every day. We're scaling these systems to support new product capabilities and lay the foundations for a more global, resilient platform, and we're looking for a senior backend engineer who can take real ownership of this complex, high-throughput work while raising the technical bar for the rest of the squad. It's a chance to shape distributed systems architecture at scale, mentor engineers around you, and build infrastructure that genuinely matters to small businesses. 🎥 Join us in our Sofia Team - get a feel for our Sofia office here . What you'll do Own and drive the end-to-end delivery of backend services within the Cards EU domain, including observability, testing, and production support Lead…

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