Backend Engineer - Sales & Orders

About the team In the Sales & Order team we build the core Sales API and Receipt engines that power the SumUp ecosystem - from hardware like POS to Solo Card Reader, from software like Online Store to Online Payments. Our mission is to translate complex transaction data into a unified "Sales" language, enabling other teams to build features independently. By connecting sales to reporting, accounting, and fiscalization, we provide the infrastructure merchants need to scale globally. You'll collaborate with a dynamic, cross-functional team of Product Manager, Engineering Manager, fellow engineers, and occasionally Product Designers and Data Analysts.  About the role As a Backend Engineer, you'll be a hands-on contributor delivering initiatives that span multiple products. You won't just be "writing code"; you'll be architecting how different SumUp products talk to each other. We are a team that believes in extreme collaboration. This means daily pair programming, high-quality "clean" engineering, and an "AI-native" mindset where we use agents and tools to accelerate our delivery. What You'll Do Develop and evolve high-performance Sales APIs and receipt engines using Kotlin and Spring Boot, ensuring they are scalable and resilient. Design and maintain robust data schemas and database interactions to handle complex transaction and sales data accurately at scale. Build and document clean, public-facing APIs that allow other engineering squads to integrate their features with the Sales Platform independently. Work on initiatives that connect transaction data with vital business systems like reporting, accounting, and global fiscalization. Spend a significant portion of your day pair programming to solve complex concurrency and architectural challenges while maintaining high code quality. Take full ownership of the development lifecycle, including writing automated tests, managing CI/CD pipelines, and monitoring service health in production. Actively use AI codin