Senior Backend Engineer - Golang

Sumup

At SumUp, the Global Bank team builds the core infrastructure and services that give merchants a digital bank account, helping small businesses manage their money easily and reliably.  The Balance Management Squad sits at the core of the Global Bank Platform. Right now, our team is completing a major milestone: consolidating and modernizing our balance management system in Europe. The next big step is creating a global transaction history service; a single, shared platform used by all regions to give merchants consistent and transparent views of their financial activity. As a (Senior) Backend Engineer, you’ll help modernize existing systems while balancing innovation with stability, collaborate with teams across regions, and build reliable services that manage diverse markets with different regulations. If you enjoy solving complex problems on high-load systems, are curious about banking, and are looking for a team that tackles challenges head-on, we’d love to hear from you. What You’ll Do * Build and evolve the SumUp’s core banking services that powers ledger operations and transactions, transforming our regional systems into a unified, scalable global platform. * Tackle complex distributed systems challenges, ensuring resilient services that continue to perform under high transaction volumes. * Support modernization initiatives by improving observability, adding test coverage, refactoring code for long-term maintainability, and gradually introducing new architectural patterns without disrupting live banking operations. * Contribute to key architectural decisions - build ledger and transaction history systems from the ground up, ensuring a globally scalable banking solution for our clients. * Collaborate with teams across Risk, Treasury, Finance, and Infrastructure to ensure smooth, compliant, and reliable global operations * Take ownership from design to production, running the services you build, monitoring their performance, and continuously improving how we deliver high-quality software at scale. You’ll be great for this role if * You have solid backend experience building reliable, high-volume services and you think carefully about system design, APIs, data modeling, and how services interact. * You are proficient in Golang and comfortable learning and working with other languages as needed, e.g. Kotlin or Elixir. * You write maintainable, well-tested code, follow CI/CD best practices, and take responsibility for the software you build from development to production. * You’re comfortable building, deploying, and running services in cloud environments like AWS using Docker and Kubernetes. * You’re eager to learn about relational databases that perform well under load and maintain data consistency. * You are a collaborator who enjoys working across regions, communicating clearly, exchanging feedback effectively, and making thoughtful technical decisions together. * You have a curiosity for building reliable financial services and banking domain It’s a plus if you have * Knowledge of Elixir - some of our legacy services are written in Elixir, and while it's not essential, it would be useful if you've worked with it before * Deeper PostgreSQL experience - we rely heavily on Postgres, so if you've done performance tuning, complex queries, or schema design, that's a plus * Experience with event streaming platforms (Kafka preferred) and modern observability stacks (Grafana, Honeycomb, etc.) Why you should join 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 Be empowered to do more that matters. At SumUp, we're on a mission to empower small businesses across the globe by providing a vast set of simple and affordable business tools to help them start, run, and grow their businesses. 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 an inclusivity and 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.

Sumup

SENIOR BACKEND ENGINEER — GLOBAL EXPANSION ABOUT THE TEAM The Global Expansion Acquiring Squad is the engine behind SumUp's growth into new markets — integrating local payment acquirers, enabling merchant onboarding, and ensuring transactions flow reliably across countries like Mexico, Canada, New Zealand, and Australia. This role sits at the heart of that mission, owning critical backend systems while also shaping how the squad works — building AI agents and developer tooling that make the entire team faster and smarter. If you're a backend engineer who wants real ownership, enjoys working in ambiguous and complex environments, and is genuinely excited about teaching AI how your codebase works (not just using it for autocomplete), this role is for you. WHAT YOU'LL DO * Design and build scalable backend services in Golang and Kotlin, covering merchant onboarding, transaction processing, and reconciliation across multiple acquirers and markets * Lead technical investigations for new market launches and mentor engineers on the team * Configure and maintain AI coding assistants (Cursor, Copilot, Continue) with team-specific rules, framework conventions, and testing patterns — so generated code fits our systems, not generic templates * Build AI agents that automate repetitive development tasks, such as generating integration stubs, updating OpenAPI specs, and flagging idempotency violations * Keep documentation accurate and AI-accessible, so the team spends less time answering "how does X work?" and more time shipping YOU'LL BE GREAT FOR THIS ROLE IF… * Strong proficiency in Golang (primary) or a JVM language such as Java or Kotlin, with experience building distributed, fault-tolerant backend systems * Experience configuring AI coding assistants at a team level — defining rules, prompts, and context packages that produce consistent, framework-compliant output * Solid understanding of idempotency, retry policies, and transaction safety in payment or financial systems * Comfort working across multiple teams and domains simultaneously, navigating ambiguity and influencing without direct authority * A track record of taking ownership in complex, cross-functional environments where the scope isn't always clearly defined 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 €2,000 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.

Sumup

SumUp builds simple, affordable financial tools that help over 4 million small businesses across 37 markets get paid, manage their money, and grow. Beyond card payments, we offer a full suite of financial products - business banking, lending, invoicing, and money transfers - giving merchants everything they need in one place.  Our Transfers Excellence squad sits within SumUp's Global Bank, and owns the core services that power how merchants and consumers move money. E.g. IBAN-based transfers, money in and out, and peer-to-peer payments via the SumUp consumer app. With the high volume transfers per hour across our European markets. That means reliability isn't a nice-to-have - it's the baseline for us. Right now, the team is replacing a set of market-specific implementations with a single, unified global transfer platform that will serve Europe, the UK, Brazil, Chile, and eventually the US and Canada.  Join our team and contribute directly to platform-level architecture that will shape how SumUp moves money at scale - work that directly impacts millions of small businesses every day. Our tech stack includes Kotlin, Java, Go, a bit of Elixir, AWS, Kafka, PostgreSQL, and Kubernetes, supported by a strong observability toolchain with Prometheus, Grafana, and Honeycomb. We also actively use AI‑assisted development tools such as Cursor, GitHub Copilot, and others. 🎥 Get a feel for life in our Berlin office. WHAT YOU'LL DO * Build and maintain backend services that sit at the heart of SumUp's transfer infrastructure, taking end-to-end ownership from development through to observability, testing and production support * Contribute to the migration from market-specific services toward a unified global transfer platform, working across a mix of active services and legacy systems being decomposed * Raise well-scoped pull requests, conduct thorough code reviews, and help maintain high standards of code quality and test coverage across the team * Participate in incident reviews and the on-call rotation, taking accountability for the reliability of the services you build * Contribute to the technical roadmap by participating in architectural discussions and proposing solutions for complex, distributed systems challenges * Apply AI tooling to accelerate your own engineering workflows and contribute to raising the team's overall AI literacy YOU'LL BE GREAT FOR THIS ROLE IF… * Solid experience as a Backend Software Engineer in modern languages (e.g. Kotlin, Go, Java, etc.). Kotlin is the team's primary language and we also work with Java, Golang, and Elixir. * Solid understanding of distributed systems and event-driven architecture. Experience with async processing and messaging tools like Kafka (or similar). * Experience working with microservice architectures, including Spring Boot and event-driven patterns, alongside solid knowledge of relational databases and API design * Comfortable working in high-throughput, regulated environments where reliability matters. Defensive coding and attention to edge cases are part of the job * Clear communicator in written and spoken English, with a collaborative approach to working across global teams  * Curious about the product impact, not just the code. Comfortable thinking about how backend decisions affect the end 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.