Senior Backend Engineer - Cards

In the Global Bank tribe, we're building the infrastructure to provide merchants with a digital business account that empowers them to manage their banking needs. Our goal is to become the most popular banking partner for small merchants globally with an effortless, simple, and affordable experience. You'll help us transition from fragmented regional setups to a unified global infrastructure, directly enabling millions of merchants worldwide to access seamless banking tailored to their needs. As a Senior Backend Engineer on the Global Accounts team, you'll own critical pieces of our bank account platform. You'll help us design and build a fully distributed, event-driven system designed to scale across regions with resilience and compliance built in. You'll work primarily in Kotlin, with opportunities in Elixir and Golang. We practice Extreme Programming: small iterations, daily deliveries, and a focus on technical design quality and deep problem understanding. Our tech stack includes Kotlin, Golang, Elixir, Java, AWS, Kafka, PostgreSQL, and Kubernetes, supported by observability tools like Prometheus, Grafana, and Honeycomb. We also use AI-assisted development tools including Cursor and GitHub Copilot. What You'll Do * Build critical infrastructure from scratch: Contribute to the design and implementation of a newly architected global accounts platform. You'll help migrate existing systems to a modern, event-driven, decoupled architecture that enables scalability and resilience across regions. * Master event-driven architecture: You'll be working extensively with Kafka to build a truly decoupled, resilient system. Event-driven architecture is essential to our goal of ensuring that failures in one part of the system don't bring down banking operations globally. This isn't just a technical requirement—it's the foundation of building a platform that can handle the complexities of multi-region banking. * Solve complex compliance challenges: Design flexible systems that handle varying regulatory and verification requirements across different regions and use cases. You'll make compliance requirements maintainable and natural rather than an afterthought. * Enable other teams: Build a self-service platform that empowers internal teams across the organization to contribute to and build on top of. * Work globally: Your work will directly impact EU and LATAM markets, with potential US expansion on the horizon. You'll Be Great for This Role If * Strong technical foundation: Solid backend development experience in Kotlin, with interest in working across multiple languages (Golang, Elixir). You understand system architecture, object-oriented and functional design principles, data modeling, and API design (RESTful and event-driven). * Event-driven architecture expertise: Proven experience with Kafka and event-driven systems. You understand how this enables true decoupling and resilience in distributed systems. * Distributed systems mastery: You've built tested, observable, scalable, robust, and fault-tolerant distributed systems. You have hands-on experience with AWS, Docker, Kubernetes, cloud-native architectures, and relational databases, understanding data consistency and performance considerations. * Ownership and craft: You take full ownership of the software you ship, from design to production readiness. You value clean, maintainable code and continuously refactor to keep designs simple and scalable. * Motivated by the challenge: You're curious and energized by complex problem-solving rather than just shipping features quickly. You thrive in environments with fast iterations and careful design, where understanding the problem deeply is valued over rushing to delivery. You're excited by the opportunity to architect critical systems from scratch and work in a team that practices Extreme Programming with daily deliveries. * Collaborative mindset: You communicate respectfully, share knowledge openly, and actively support your teammates' growth. Why you’ll enjoy working at SumUp * Be part of a company that values diversity and celebrates unique perspectives. * Work with a global team of skilled professionals in an environment that fosters collaboration, learning, and growth. * Be part of a global tribe building a banking solution from the ground up and delivering impactful solutions to the real-life problems of millions of SumUp merchants all over the world * Career growth and learning opportunities: We invest in your development through regular training, mentorship programs, SumUp University leadership cohort and a yearly learning budget (2,000 EUR) * Sabbatical program for tenured SumUppers * Join a global team where you belong: Check out our D&I Initiatives and Employee Resource Groups such as Pride Club, SumAfro, Neurodiversity, Grupos Mais, Women in Tech, and more * Health & wellness benefits: in-house fitness classes, gym in the office, subsidized Urban Sports Club and available psychotherapy sessions * A lot of other benefits such as Subsidized Public Transport Card, Kita placement assistance, Pension Scheme, Language Learning platform/courses etc. * Enrollment onto our virtual stock ownership program - you will own a stake in SumUp’s future success About SumUp About SumUp At SumUp, we’re on a mission to empower small businesses around the world with simple, affordable tools to help them start, run, and grow. More than 4 million merchants across 37 markets trust us as their financial partner — and we’re just getting started. We’re a global team of 3,000+ people from over 90 nationalities, united by curiosity, collaboration, and care. Our core valuesOpens in new window and cultureOpens in new window shape everything we do, fostering inclusion, learning, and belonging. SumUp is proud to be an Equal Employment Opportunity employer, committed to building a safe, respectful, and diverse workplace where everyone can thrive. 👉 Explore more about our culture on our careers site, or follow us on LinkedInOpens in new window and InstagramOpens in new window. SumUp is proud to be an Equal Employment Opportunity employer, actively seeking and embracing diversity in our workforce. We don't make hiring or employment decisions based on race, colour, religion or religious belief, ethnic or national origin, nationality, sex, gender, gender identity, sexual orientation, disability, age or any other basis protected by applicable laws or prohibited by company policy. Our commitment extends beyond recruitment to creating a safe and respectful workplace where harassment of any form is strictly prohibited.   Job Application Tip We recognise that candidates feel they need to meet 100% of the job criteria in order to apply for a job. Please note that this is only a guide. If you don’t tick every box, it’s ok too because it means you have room to learn and develop your career at SumUp.

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. 🎥 Get a feel for our Berlin 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 delivering production-ready backend services end-to-end, including testing, monitoring, and maintenance, on a modern cloud-native stack * Production experience with Kotlin and interest in working with a number of other languages (Java, Golang and Elixir) * 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 WHY YOU SHOULD JOIN SUMUP * 🌎 Opportunity to work with SumUppers globally on large-scale fintech products used by millions of businesses worldwide, from our Berlin 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 for your individual development, which can be used to attend conferences and/or advance your career through further education * 💶 A corporate pension scheme where we match up to 20% of your contributions * 🏖 Generous time off: enjoy 28 days of paid leave plus public holidays and special leave days * 🏃 Numerous other benefits such as Urban Sports Club subsidy, Kita placement assistance, subsidised office lunches * 🌴 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 tools that allow them to thrive. Today, over 4 million businesses in 37 markets rely on SumUp as their financial partner to manage payments, finance and customer relationships. Our commitment to small businesses is reflected in our diverse team of over 3,000 SumUppers from over 90 nationalities, united by global collaboration and an innovative mindset. Our core values lay the foundation for who we are and what we stand for, shaping our work culture and driving our success. We foster inclusivity and a continuous learning culture, providing a safe space for personal and professional growth. Our differences make us unique and strong as we strive to create an environment where everyone belongs and feels supported, no matter how they identify. SumUp is proud to be an Equal Employment Opportunity employer, actively seeking and embracing diversity in our workforce. We don't make hiring or employment decisions based on race, colour, religion or religious belief, ethnic or national origin, nationality, sex, gender, gender identity, sexual orientation, disability, age or any other basis protected by applicable laws or prohibited by company policy. Our commitment extends beyond recruitment to creating a safe and respectful workplace where harassment of any form is strictly prohibited. Discover more about our culture and opportunities on our careers website, and follow our journey on LinkedIn, Instagram, and TikTok. Job Application Tip We recognise that candidates feel they need to meet 100% of the job criteria in order to apply for a job. Please note that this is only a guide. If you don’t tick every box, it’s ok too because it means you have room to learn and develop your career at SumUp.