Senior Full-Stack Engineer (Berlin)

Sumup

The Sidekick team builds and owns the progressive web app that SumUps field sales agents rely on every day, a tool that brings together everything a seller needs in one place: creating offers on the go, signing up new merchants, managing hardware sales, and tracking commissions in real time. It's one of our most impactful internal products, sitting at the heart of a primary revenue driver for the business. As our Senior Full Stack Engineer, you'll take genuine ownership of features end-to-end, from scoping through to production, working closely with product, engaging directly with sales stakeholders, and having a real say in what gets built and why. If you want autonomy, meaningful scope, and work that directly enables the people driving SumUp's growth, this is the role. What you'll do * Build and maintain features across the full stack of our progressive web app, spanning the field sales experience, back office tooling for sales agents, and emerging LLM-powered support tooling, owning work from scoping through to production * Participate actively in product discovery, joining user research sessions, reviewing usage data, and contributing to prioritisation discussions alongside product * Work directly with sales stakeholders to understand their needs, distinguish between what's requested and what's actually needed, and propose solutions with clear trade-offs * Contribute to raising engineering standards across the team, through documentation, code quality, and proactive process improvements * Integrate with external systems such as Salesforce where required, and help shape how data flows across domains to create a consistent experience for field sellers You'll be great for this role if * Hands-on experience with a full-stack framework, Next.js, Remix, Nuxt, or similar, with a clear track record of shipping real-world features end-to-end. * Strong, proven experience with React and TypeScript, building scalable, maintainable applications in a production environment. * Experience building or consuming RESTful APIs and working within complex micro service systems, familiarity with Go is welcome. * Comfortable as a Kubernetes user, with exposure to working in cloud-native, distributed environments. * Experience working in a product-led or dual-track agile team alongside our product team, contributing to product decisions, not just technical ones. * A natural tendency to reach out to stakeholders, ask the right questions, and bring genuine empathy to the end user's experience. * Comfortable showcasing and demoing work, and always looking for ways to simplify or automate where it makes sense. Why you should join SumUp: * 🌎 Opportunity to work with SumUppers 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 * 🚀 Enrolment onto our Virtual Stock Option programme: you will own a stake in SumUp's future success * 📚 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 SumUp team About SumUp Be empowered to do more that matters. At SumUp, 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 SumUp 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 SumUppers 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. SumUp 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 LinkedIn, Instagram, and TikTok 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. 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.

Sumup

The SuperApp squad owns parts of the merchant experience across Web, Android, iOS and the flows that millions of small business owners use every day to run and grow their businesses. As our dedicated full stack web engineer within the squad, you'll own this space entirely, shaping technical direction, driving feature parity for SumUp's web experience. If you want real ownership, a broad scope, and work that lands directly in the hands of millions of merchants, this is the role. 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 * 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 — 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 WHAT WE'RE LOOKING FOR: * Strong, proven experience with React.js and TypeScript, building scalable, maintainable applications in a production environment. * Comfortable working across the stack, with experience building backend services or REST APIs, Go is a plus, but Node.js or similar is equally welcome. * Ability to navigate and refactor complex codebases with a focus on clean, durable code and solid system design. * Experience working in cross-functional teams alongside product managers and designers, with a strong sense of ownership and comfort with ambiguity. * A product mindset, thinking about the merchant experience, not just the code, and connecting technical decisions to real business outcomes. WHY YOU SHOULD JOIN SUMUP: * 🌎 Opportunity to work with SumUppers 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 * 🚀 Enrolment onto our Virtual Stock Option programme: you will own a stake in SumUp's future success * 📚 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 SumUp team ABOUT SUMUP Be empowered to do more that matters. At SumUp, 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 SumUp 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 SumUppers 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. SumUp 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 LinkedIn, Instagram, and TikTok. 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.

Sumup

Our Billing and Subscriptions team sits at the heart of how SumUp's merchants pay for, manage, and grow with our products. We own the billing engine, merchant wallet, and subscription experiences that underpin millions of transactions across 37 markets, and right now, we're in an exciting phase of rebuilding and expanding that foundation. We're deepening our billing capabilities to support new sales models, market expansions, and financial integrations that directly shape how small businesses experience SumUp — and this role is central to making that happen. What you'll do * Build and maintain backend services and frontend interfaces across our billing, contracts, and merchant wallet products * Contribute to the refactoring of key billing components to improve reliability, data security, and alignment with our wider payments platform * Support the expansion of our billing and wallet capabilities into new markets, helping ensure localisation requirements are met * Take part in our weekly support rotation, handling incoming customer queries and helping maintain platform stability * Work closely with senior engineers and product managers to deliver features end-to-end, from implementation through to production You'll be great for this role if * 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 databases such as PostgreSQL or MySQL and non-relational databases (such as DynamoDB, MongoDB, or Redis). * Practical frontend experience working with React and Next.js, with the ability to write clean, typed code in TypeScript 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. Why you should join SumUp * 🌎 Opportunity to work with SumUppers 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 SumUp team About SumUp Be empowered to do more that matters. At SumUp, 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 SumUp 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 SumUppers 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. SumUp 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 LinkedIn, Instagram, and TikTok. 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.