Software Engineer

SumUp; Berlin (NH); On-site; USD 127,000 - 173,000; Full time

Benefits offered by this job

Equity option

L&D budget €2,000

Pension match up to 20%

28 days leave

Urban Sports Club

Break4me sabbatical

Referral bonus

Job summary

SumUp in Berlin is seeking a Senior Backend Engineer for the Global Expansion squad to own core backend services across markets.

You’ll design in Golang/Kotlin, mentor peers, and shape AI tooling integration to accelerate market launches while ensuring reliability and security in financial transactions.

Join an office-first team committed to diversity, ongoing learning, and building scalable fintech infrastructure used by merchants worldwide.

Qualifications

• Backend experience with scalable distributed systems.
• Experience with payment/fintech or transaction safety.
• Mentorship and ownership in cross-functional teams.

Responsibilities

• Design and build scalable backend services in Golang and Kotlin for onboarding, transactions, and reconciliation across markets.
• Lead technical investigations for new market launches and mentor engineers on the team.
• Configure and maintain AI coding assistants with team-specific rules, prompts and context.
• Build AI agents that automate repetitive development tasks like integration stubs and API spec updates.
• Keep documentation accurate and AI-accessible to reduce time answering how X works.

Skills

Golang

Kotlin

Java

Tools

Cursor

Copilot

Continue

Job description

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.