Backend Developer

SumUp provides simple and affordable financial tools that help small businesses manage payments, finance, and customer relationships. Its services are used by over 4 million businesses across 36 markets.

• Aggregate data across the SumUp ecosystem to identify which acquisition channel or sales agent drove merchants to valuable actions;
• Establish data models, API contracts, and rules to automate commission workflows for sales agents, partners, and merchant referrals;
• Build the Lifecycle Event Log with the Merchant Intelligence squad, creating a centralized store of curated merchant lifecycle events for attribution, recommendations, customer support, and sales;
• Build internal back offices and APIs for sales representatives and leaders to monitor commissions, modify commission plans, manage portfolios, and resolve disputes;
• Define and document API contracts, schemas, and integration patterns for other engineering teams;
• Establish testing, observability, and incident response best practices within the new squad;
• Use AI and agentic coding tools to scaffold services, write tests, explore unfamiliar code, and draft documentation while maintaining accountability for shipped work.

• Strong backend engineering background in Go, or experience with a typed language and readiness to ramp up quickly;
• Experience designing APIs and distributed systems with clear contracts, versioning, and integration patterns;
• Proficiency with relational and analytical databases, including PostgreSQL and Snowflake, and ability to select the right database for each use case;
• Experience building Kafka-based event-driven systems and understanding of event sourcing and CDC patterns;
• Experience with auditable, high-trust systems in fintech, payments, or similar domains;
• Experience building services from scratch in greenfield, early-stage squads with limited prior context;
• Experience with testing, observability, and incident response practices;
• Ability to take end-to-end ownership, adapt to shifting priorities, bridge technical and non-technical audiences, explain trade-offs, and make pragmatic decisions;
• Mentorship instincts and ability to raise the bar for colleagues.

• Work from the Berlin office in an office-first setup;
• Hack Days every second Friday and global Hack Weeks;
• Annual L&D budget of €2,000 for conferences and/or further education;
• Enrolment in the VSOP program, offering a stake in SumUp’s future success;
• Corporate pension scheme matching up to 20% of contributions;
• 30-Day sabbatical after completing 3 years of employment;
• Referral bonus;
• Other benefits include an Urban Sports Club subsidy, Kita placement assistance, relocation assistance, and subsidised office lunches.