Senior Backend Engineer - Global Expansion

About the role

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. This role owns critical backend systems while also shaping how the squad works — building AI agents and developer tooling that make the entire team faster and smarter.

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
• 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

What you'll need

• 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

What they offer

• Stock Option programme with ownership stake in SumUp's future
• Annual L&D budget of €2,000 for conferences and further education
• Corporate pension scheme with up to 20% matching
• 28 days paid leave plus public holidays and special leave days
• Urban Sports Club subsidy, Kita placement assistance, subsidised office lunches
• 1-month sabbatical after 3 years of service