Senior Backend Engineer

Your responsibilities

• Design, build, and maintain scalable backend systems supporting SumUp’s Bookings product
• Collaborate with frontend and mobile engineers to deliver new features and improve APIs across web, iOS, and Android
• Participate in technical planning, code reviews, and design discussions to ensure clean, testable, and maintainable code
• Continuously optimise performance, ensure observability, and uphold our high reliability standards
• Actively contribute to shaping the technical roadmap for the Sell Online platform

Our requirements

• You have 5+ years of professional backend engineering experience
• You’re fluent in Java or Kotlin and have experience with Spring Boot
• You’ve worked with PostgreSQL, Kafka, Docker, Kubernetes, and AWS
• You understand RESTful APIs, distributed systems, and event-driven architectures (e.g. CQRS, Event Sourcing)
• You bring experience with CI / CD pipelines, GitHub Actions, and observability tools like Grafana or Honeycomb
• You thrive in collaborative teams, enjoy mentoring peers, and care about delivering real value to merchants

Optional

• Familiarity with gRPC, Protobuf, or performance optimisation at the backend / database level

This is how we organize our work

This is how we work

• you have influence on the product
• agile

This is how we work on a project

• code review
• DDD
• event modeling
• documentation
• issue tracking tools

Development opportunities we offer

• conferences in Poland
• industry-specific e-learning platforms
• space for experimenting
• substantive support from technological leaders
• technical knowledge exchange within the company
• time for development of your ideas

What we offer

• Opportunity to work , from our vibrant Warsaw office with inspiring art-filled lounges and a skyline terrace in the Mennica Legacy Tower.
• 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 VSOP program : you will own a stake in SumUp’s future success
• Fitness support : work out on-site at our gym or explore the city using the Multisport Card, subsidised by SumUp for access to sports facilities across Warsaw
• Commitment to well-being : access health insurance coverage for you and your family, plus life insurance to further protect your peace of mind
• PPK (Employee Capital Plan) : grow your savings with joint contributions from SumUp and the State.
• Generous time off : enjoy 26 days of paid leave plus public holidays and special leave days Break4me : 1-month sabbatical after 3 years of service
• Referral Bonus : earn additional rewards by referring talented individuals to join the SumUp team

sharing the costs of sports activities

private medical care

sharing the costs of professional training & courses

life insurance

coffee / tea

VSOP program

Break4me : 1-month sabbatical after 3 years of service

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.
• 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.

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