Senior Backend Engineer - Identity Lifecycle

About the team: You’ll join one of the teams within SumUp’s Identity Lifecycle Mission, working on some of the most critical building blocks behind the merchant journey, from onboarding and identity verification to KYC/KYB, regulatory data collection, and managing customer identity throughout the entire lifecycle. Today, many of these capabilities live across different flows, legacy services, and tightly coupled integrations. We’re on a journey to bring these pieces together into a more coherent, scalable platform, with shared data models, reusable services, and clear ownership boundaries. As a Senior Backend Engineer, you won’t just be maintaining existing systems. You’ll have the opportunity to shape how our identity platform evolves, modernise critical services, and help build foundations that can support new regulations, markets, and product requirements without reinventing the wheel every time. You’ll be part of one dedicated team, but the challenges we tackle often cross team and domain boundaries. You’ll work closely with Engineers, Product, Design, Compliance, Risk, and Operations, giving you the opportunity to influence solutions well beyond your own team. If you enjoy solving complex backend problems, working in a highly collaborative environment, improving reliability, and building scalable capabilities that enable other teams to move faster, this could be an exciting opportunity to make a real impact at SumUp. What you’ll do: • Design, build, and operate scalable backend services, APIs, event-driven workflows, and system integrations. • Build reusable capabilities that power merchant onboarding, identity verification, and KYC/KYB regulatory data collection. • Drive reliability and resilience across critical services through better observability, failure handling, incident response, and long-term risk reduction. • Work primarily with Go, while maintaining and progressively modernising existing services written in Java. • Evolve domain models and service boundaries while reducing legacy complexity, duplicated logic, and tightly coupled integrations, always with a pragmatic, incremental mindset. • Own your work end-to-end, from technical design and implementation to rollout and production follow-up. • Work across team and domain boundaries, turning ambiguous product and regulatory requirements into clear, scalable technical solutions. • Review code and designs, mentor engineers, and help raise engineering standards across the mission. You’ll be great for this role if you have: • Strong professional experience building and operating production backend systems with high business impact. • Experience working with Go and Java and confidence in maintaining and evolving existing Java services. • Strong knowledge of API design, distributed systems, asynchronous processing, data modelling, testing, and system design. • Experience with event streaming platforms such as Kafka and modern observability tools such as Grafana or Honeycomb. • Experience deploying and operating services in cloud environments such as AWS, ideally with Docker and Kubernetes. • A strong ownership mindset, with the ability to take complex problems from definition through to production. • Experience improving the reliability of business-critical systems and turning recurring incidents into lasting engineering improvements. • Strong communication skills and a collaborative approach to working across Engineering, Product, Compliance, Risk, and Operations. Nice to have: • Experience in fintech, payments, KYC/KYB, identity verification, or regulatory systems. • Experience translating regulatory and compliance requirements into clear, scalable engineering solutions, while helping bridge the gap between Compliance and Engineering. 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 🧑‍🔬 We take learning and experimentation seriously with Hack Days every second Friday, and entire global Hack Weeks. 🌈 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 📚 A dedicated annual L&D budget of €2,000 for attending conferences and/or advancing your career through further education 🚀 Enrolment onto our VSOP program: You will own a stake in SumUp’s future success 💶 A corporate pension scheme where we match up to 20% of your contributions 🔄 30 Days Sabbatical: Enjoy the unique opportunity to take a well-deserved break with our 30 days sabbatical benefit after completing 3 years of employment with SumUp 🔗 Referral Bonus: Earn additional rewards by referring talented individuals to join the SumUp team 🚵🏾‍♂️ Numerous other benefits such as Urban Sports Club subsidy, Kita placement assistance, relocation assistance, subsidised office lunches SumUp is an Equal Employment Opportunity employer that proudly pursues and hires a diverse workforce. SumUp does not make hiring or employment decisions on the basis of 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. SumUp also strives for a healthy and safe workplace and strictly prohibits harassment of any kind. About us: 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 36 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. Explore career opportunities with us and join a team driven by collaboration, innovation, and a shared vision of creating a world where everyone can build a thriving business. Discover more about our vibrant and inclusive work culture and how we work on our careers website, and follow our journey on LinkedIn and Instagram. 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.