Senior Frontend Engineer – Sell Online

About the Team

You'll join the Sell Online Tribe, the group shaping how merchants bring their businesses to life online. We design and build tools that help millions of entrepreneurs, from barbers to bakers, sell their products and services anywhere.

You'll be working on some of SumUp's biggest merchant-facing online products as part of the Bifrost team, contributing to growing and scaling critical products like Payment Links and Gift Cards, while also working on integration products that provide essential features used across many other SumUp products. They're high-traffic, high-responsibility products that other SumUp teams depend on too.

You'll join a small, cross-functional team and take on genuine ownership of the frontend - not just executing tickets, but shaping how the products evolve.

What You'll Do

• Build and maintain frontend features across payment links, gift cards, and online checkout products, writing clean, testable, and maintainable code
• Contribute to the development and upkeep of integration products and SDKs, used by both internal teams and external partners
• Take part in technical planning, design reviews, and sprint ceremonies
• Help reduce tech debt and improve application performance, observability, and accessibility
• Monitor live services and respond to issues, providing redundancy for customer support requests reaching the team

You'll Be Great for This Role If…

• You have 5+ years of experience in TypeScript and JavaScript, with hands-on experience building production-grade React and Next.js applications (including SSR and app router patterns)
• You have experience writing unit, integration, and end-to-end tests using tools like Jest, Vitest, or React Testing Library
• You're comfortable working within CI/CD workflows and collaborating in agile environments (Scrum or Kanban)
• You have experience with UI libraries such as Radix or shadcn, and a solid understanding of accessibility and UX best practices
• You have a product mindset - someone who cares about the value delivered to merchants, and who can work autonomously to drive complex features end-to-end

Why You Should Join SumUp

• Opportunity to work in a truly global, multicultural team from the open, vibrant Cologne office (office-first setup)
• Commitment to Diversity and Inclusion
• Enrolment onto the Virtual Stock Option programme
• A dedicated annual L&D budget of €2000
• Generous time off: 28 days of paid leave plus public holidays and special leave days
• Subsidised mobility options like discounted transport tickets or bike leasing
• Access to fitness via Urban Sports Club
• Corporate pension scheme with SumUp contributing an extra 20% on top of your contribution
• Employee perks via Corporate Benefits platform
• Break4me: 1-month sabbatical after 3 years of service
• Referral Bonus

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 diverse team of over 3,000 SumUppers from over 90 nationalities is united by global collaboration and an innovative mindset.