Full Stack Engineer

Our Purchase squad owns the end-to-end checkout and buying experience across Sum Up's platforms, from self-service journeys to sales-assisted flows, covering everything from hardware and subscriptions to bundled offers and promotions. We're in an active phase of stabilising and scaling our commerce platform, reducing complexity, and building the foundations that allow us to move faster and serve merchants better across multiple markets.

This is a backend-leaning full stack role where you'll work on real, impactful problems that sit right at the centre of how merchants discover, buy, and manage Sum Up's products.

• Build and maintain frontend and backend components that power our checkout and purchase flows across self-service and sales-assisted channels
• Contribute to core commerce capabilities including subscription promotions, bundled offers, and order lifecycle improvements
• Help improve platform reliability and reduce technical complexity, addressing recurring issues and supporting ongoing migrations
• Work closely with product managers, designers, and engineers to deliver scalable, high-quality features across multiple markets
• Improve merchant-facing experiences, including better visibility into orders, invoices, and tracking information

• Solid experience building full stack applications, with a backend focus. Ideally comfortable with Node.js or Go, though we're open to other backend languages.
• Comfortable working with both relational and non-relational databases.
• Practical frontend experience working with React or Next.js, with the ability to write clean, typed code in Type Script or JavaScript.
• Strong communication skills in English, both written and spoken, with the ability to give and receive clear, constructive feedback.
• A pragmatic approach to problem-solving — able to make sensible trade-offs, unblock yourself and others, and write clean, maintainable code.

• Opportunity to work with Sum Uppers 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
• A dedicated annual L&D budget of €2000 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 Sum Up team

Be empowered to do more that matters.

At Sum Up, 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 Sum Up 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 Sum Uppers 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.

Sum Up 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 Linked In, Instagram, and Tik Tok.

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 Sum Up.