Senior Full-Stack Engineer - SuperApp

DEINE AUFGABEN Responsibilities: * Design, develop, and maintain scalable web applications using modern frontend and backend frameworks. * Implement micro-frontend architectures and integrate with distributed backend services. * Build and consume RESTful APIs; ensure robust automated testing across the stack. * Contribute to CI/CD pipelines and cloud-native deployments. * Participate in code reviews, architectural discussions, and continuous improvement. DEIN PROFIL Requirements: * Strong experience with component-based frontend frameworks and typed languages (React, TypeScript, and modern frontend tooling) * Proficiency in backend development with Python or similar languages; familiarity with both synchronous and asynchronous patterns. * Solid Experience with Agentic Coding in a production setting * Experience with containerization, orchestration, and cloud infrastructure. * Solid understanding of micro-frontend and microservice architectures. * Familiarity with automated testing, code quality tools, and collaborative workflows. * Ability to work with both legacy and modern systems, and automate repetitive tasks. * You can’t imagine working without agile methods * You care deeply about software craftsmanship, including clean code, TDD, and continuous delivery * You actively practice the DevOps mindset * English with at least B2 level, German is a big plus Nice to Have: * Proficiency in other languages (Kotlin, Go, Rust)  * Knowledge about CQRS/event sourcing pattern * Experience with infrastructure automation and cloud platforms, and Infrastructure as Code * Knowledge of educational technology or large scale SaaS platforms. On Site Expectation: Enjoy flexible hybrid work, with up to 2 remote days per week. You need a working permission in Germany by EU-Nationality or any other means and have to be willing to relocate if you don't live already in the Berlin area. WARUM WIR? At bettermarks, you help build a product with real educational impact, empowering students in grades 4–12 to succeed at school. Our mission: to make individualized support easier for teachers and to provide students with an intuitive and effective learning experience. You can expect: * An international team of developers, educators, mathematicians, and digital experts. * A centrally located workplace in the heart of Kreuzberg with excellent public transport connections. * Home office days and flexible working hours. * Collaboration in an open team with flat hierarchies. * 28 vacation days with additional 2 days (Xmas Eve and NY Eve) off * Enjoy unlimited travels with our Employer-subsidized Germany Ticket (Deutschland Job Ticket) for nationwide public transport * Stay healthy with our subsidized Urban Sports Club membership for fitness and wellbeing * We offer a corporate pension schema  * Get corporate discounts on hundreds of products of top brands

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.