Backend engineer for card issuing

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.

• 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

• Solid, hands-on experience delivering production-ready backend services end-to-end, including testing, monitoring, and maintenance, on a modern cloud-native stack
• Production experience with Kotlin and an openness to work with additional languages such as Elixir, Java or Golang.
• Solid understanding of distributed systems, API design, data modelling, and working with relational databases
• Hands on experience in containerisation, orchestration, and CI/CD practices
• Ability to take an ambiguous product problem, define the technical approach, and lead it through to implementation with minimal guidance
• Comfort working across teams and communicating clearly in written and spoken English in a professional setting
• Genuine curiosity about the product domain — comfortable applying a backend lens during feature refinement and thinking beyond the code to understand how your work shapes the user experience

• 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