Software Engineer

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 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 are 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. You will operate with a high degree of autonomy, making technical decisions that directly influence how new acquiring markets are launched and how the squad collaborates with AI to accelerate delivery. You will partner closely with product, compliance, and other engineering teams to translate complex requirements into resilient backend solutions. This position is ideal for someone who thrives on ownership, enjoys mentoring peers, and is motivated by building systems that handle real-world financial scale and reliability demands.

Key facts

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 to elevate the overall capability of the squad.

Configure and maintain AI coding assistants such as Cursor, Copilot, and Continue with team-specific rules, framework conventions, and testing patterns so generated code fits our systems rather than relying on generic templates.

Build AI agents that automate repetitive development tasks, including generating integration stubs, updating OpenAPI specifications, and flagging idempotency violations before they reach production.

Keep documentation accurate and AI-accessible so the team spends less time answering "how does X work?" and more time shipping features that matter.

Collaborate closely with product managers and stakeholders to clarify requirements and translate them into robust technical designs that support global acquiring workflows.

Implement observability, monitoring, and alerting for critical payment flows to ensure reliable transaction processing and rapid troubleshooting across markets.

Partner with compliance and risk teams to ensure that backend systems adhere to local regulations and financial standards in each new market.

Own and evolve the architecture of core services to support scalability, performance, and security as the business expands into additional countries.

Facilitate knowledge sharing within the squad through code reviews, pair programming, and documentation that keeps best practices up to date and easily discoverable.

Contribute to the definition and improvement of engineering processes, including deployment pipelines, testing strategies, and API design standards.

Act as a technical owner for key integrations with external acquirers, ensuring contracts, error handling, and retry logic are reliable and well-documented.

Support on-call responsibilities and incident response, working with the team to identify root causes and implement preventative measures.

Encourage continuous improvement by experimenting with new tools, measuring their impact, and adopting practices that increase the team's efficiency and confidence in releasing changes.

Requirements

Strong proficiency in Golang (primary) or a JVM language such as Java or Kotlin, with experience building distributed, fault-tolerant backend systems that handle financial transactions.

Experience configuring AI coding assistants at a team level, including defining rules, prompts, and context packages that consistently produce framework-compliant output aligned with your technology stack.

Solid understanding of idempotency, retry policies, and transaction safety in payment or financial systems to prevent duplication and ensure correctness under failure conditions.

Comfort working across multiple teams and domains simultaneously, navigating ambiguity and influencing without direct authority while maintaining alignment on shared objectives.

A track record of taking ownership in complex, cross-functional environments where the scope is not always clearly defined and decisions must be made with incomplete information.

Ability to write clean, maintainable code and design APIs that are well-documented and easy for other engineers to adopt and extend over time.

Experience collaborating with compliance, risk, and product teams to ensure that backend implementations meet regulatory and business requirements.

Strong problem-solving skills and a methodical approach to debugging production issues, supported by logging, metrics, and traceability of financial operations.