Senior Backend Engineer - Golang

About the team You’ll join the Sell Online Tribe , the group shaping how merchants bring their businesses to life online. We design and build tools that help millions of entrepreneurs, from barbers to bakers, sell their products and services anywhere . Our focus is on Online Store and Bookings, two products at the heart of SumUp’s ecosystem. Together, they give merchants the power to manage appointments, showcase their offerings, and get paid—all from their phones. We’re a cross-functional team of Product Managers, Designers, and Engineers who move fast, collaborate openly, and care deeply about crafting beautiful mobile experiences. As part of this team, you’ll help us expand into new verticals, close the gap between web and mobile, and make digital selling effortless for small businesses everywhere. About the role You will be working on some of SumUp's biggest merchant-facing online products as part of the Bifrost team. You'll contribute to growing and scaling critical products like Payment Links, Virtual Terminal, and Unified Gift Cards, while also working on integration products that provide essential features used across many other SumUp products. You're a developer who values reliability, collaboration, and continuous improvement. You bring backend expertise and thrive in a high-impact environment where your work directly supports merchant success and team scalability. What you'll do Provide redundancy for the scalability and continuous growth of some of the high-pri online products in SumUp Contribute to the implementation, growth and integration of Online Checkouts throughout SumUp Actively participate in planning and reviewing sessions on quarter and sprint levels by providing constructive feedback and estimations Monitor existing services and make necessary fixes to ensure platform reliability Implement new features with maintainable and testable code Optimize and improve application performance for scalability Participate in code reviews to keep high code quality standards You'll thrive in this role if: You have 5+ years experience in backend engineering with Golang You have a strong understanding of fundamental system architecture, design principles, data modeling, and API design You have strong experience with distributed and fault-tolerant systems You have user-level experience working with AWS and Kubernetes You have good knowledge of Kafka Postgres You're passionate about building products that help small businesses succeed and grow Why you should join SumUp: 🌍 Opportunity to work with SumUppers globally on large-scale fintech products used by millions of businesses worldwide, from our Cologne 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 LD budget of €2,000 for attending conferences and/or advancing your career through further education 🚀 Enrollment 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 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 deve ... (truncated, view full listing at source)