Senior Full-Stack Engineer

About the role

You will own the SuperApp squad's contribution to the merchant experience across Web, Android, iOS, and the flows that millions of small business owners rely on daily to run and grow their businesses. You will shape technical direction for the web within this squad, driving feature parity and delivery for SumUp's web experience with a broad scope and direct impact. This role grants you real ownership over critical user journeys, ensuring your work lands directly in the hands of millions of merchants worldwide. You will be expected to operate with product mindset and cross-functional leadership, turning ambiguous problems into well‑defined solutions. If you want responsibility that scales and work that matters at scale, this is the role.

Key facts

What you'll do

• Own and develop core web dashboard features including the first-time user experience, home screen widgets, quick actions, tools section, and communications centre.
• Build and maintain the backend services that power these flows, ensuring a seamless and consistent experience across web and mobile platforms.
• Work closely with iOS and Android engineers, product managers, and designers to shape cross-platform solutions and contribute to technical direction.
• Lead the design and refinement of technical solutions by writing clear documentation, making architectural decisions, and communicating progress to stakeholders.
• Be an active contributor to the web chapter and the broader engineering community at SumUp, sharing knowledge and raising standards.
• Translate product and designer requirements into robust, scalable frontend architectures that balance performance, maintainability, and merchant needs.
• Implement reliable backend services and REST APIs, evaluating technologies such as Go or Node.js where appropriate to serve the SuperApp ecosystem.
• Navigate and refactor complex legacy codebases while enforcing clean, durable code and solid system design principles.
• Partner with cross-functional teams alongside product managers and designers, embracing ambiguity and taking ownership of end-to-end delivery.
• Connect technical decisions to real business outcomes by thinking about the merchant experience beyond the code and validating impact.

Requirements

• Demonstrate strong, proven experience with React.js and TypeScript, building scalable, maintainable applications in a production environment.
• Show comfort working across the full stack, with experience building backend services or REST APIs, where Go is a plus but Node.js or similar is equally welcome.
• Prove ability to navigate and refactor complex codebases with a focus on clean, durable code and solid system design.
• Exhibit experience working in cross-functional teams alongside product managers and designers, with a strong sense of ownership and comfort with ambiguity.
• Maintain a product mindset that thinks about the merchant experience, not just the code, and connects technical decisions to real business outcomes.
• Communicate clearly and professionally in English, both in writing and during collaborative discussions with global stakeholders.
• Be comfortable working from Berlin in an office-first setup while engaging with distributed teams across regions.
• Align with SumUp's commitment to Diversity and Inclusion, contributing to a respectful and inclusive workplace.

Nice to have

• Experience contributing to large-scale fintech products used by millions of businesses worldwide.
• Familiarity with financial products, payments, or monetization flows in high‑volume environments.
• Active involvement in open source or public technical writing that demonstrates thought leadership.

Practical notes

• This is a full-time role based in Berlin, Germany, with an office-first setup.
• No specific visa or travel requirements are outlined in the source material.
• Applicants are encouraged to refer talented individuals through SumUp's referral bonus programme.
• Upon successful completion of three years of service, you become eligible for a one-month sabbatical through the Break4me programme.
• An annual Learning and Development budget of €2000 is available for conferences or further education.
• Additional benefits include a corporate pension scheme with company matching, Urban Sports Club subsidy, Kita placement assistance, and subsidised office lunches.