On Lead Backend Engineer - POS Platforms Integration

At On, retail isn't just a channel-it's an experience. As we scale our global footprint, we're laying the foundation for a future-ready Point of Sale (POS) ecosystem. To do that, we need robust backend systems that orchestrate flawless integration between the physical and digital, the store and the cloud. We're looking for a Backend Engineer to drive the integration of our POS platform with mission-critical systems like ERP, OMS, CRM, and loyalty engines. You'll architect and build resilient services, shape our event-driven data flows, and ensure our store operations stay fast, reliable, and future-proof. Based in Berlin, you'll be joining the Retail Experience team-where technology meets the shop floor and every request matters. If you love crafting clean APIs, streamlining integrations, and optimizing real-world system performance, you'll feel right at home., * Backend & Integration Engineering: Design, build, and scale backend services that power POS integrations across ERP, eCom, CRM, inventory, and loyalty platforms Develop REST and GraphQL APIs that are performant, secure, and easy to consume Implement real-time and batch data sync, authentication flows (OAuth, SSO), and secure event pipelines

• Architecture & Resilience: Contribute to the design of a cloud-native, event-driven architecture for global retail operations Build scalable integration patterns using message queues (Kafka, RabbitMQ) and serverless workflows Support observability through proactive monitoring, alerting, and performance tuning (e.g., NewRelic)
• Testing & Quality Automation: Ensure reliability through a robust automated testing stack: contract tests, load tests, and test data pipelines Collaborate with QA and DevOps to streamline CI/CD and improve release confidence Participate in incident response and post-mortem analysis to continuously harden platform stability
• Collaboration & Strategy: Partner with frontend, product, and vendor teams to align integration design with platform capabilities Influence technical decisions during vendor evaluations and rollout phases Impact roadmap decisions by sharing technical insights and platform implications Actively contribute to the broader architecture vision for On's composable commerce technology stack

• 3+ years of backend engineering experience with modern technologies (Node.js, TypeScript, or similar)
• Proven track record integrating APIs across commerce, ERP, OMS, or CRM domains
• Familiar with headless commerce, microservices, and composable architecture principles
• Experience with message brokers (Kafka) and asynchronous data processing
• Solid understanding of databases (e.g., PostgreSQL) and infrastructure-as-code tools (Terraform)
• Skilled in designing, scaling, and monitoring cloud-native services (AWS, GCP, or Azure)
• Familiarity with OAuth2, token-based authentication, and secure service design
• Strong debugging and telemetry skills: logs, traces, metrics, and real-time alerting