Senior Backend Engineer – POS Platforms Integration

In short

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.

Your mission

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

Your story

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

What We Offer

On is a place that is centered around growth and progress. We offer an environment designed to give people the tools to develop holistically – to stay active, to learn, explore and innovate. Our distinctive approach combines a supportive, team-oriented atmosphere, with access to personal self-care for both physical and mental well-being, so each person is led by purpose.

On is an Equal Opportunity Employer. We are committed to creating a work environment that is fair and inclusive, where all decisions related to recruitment, advancement, and retention are free of discrimination.