On - Lead Backend Engineer – POS Platforms Integration - London

Team for Career Site

Technology

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.
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

Meet the team

At On, we don’t just create tools—we craft experiences that move the world. As part of our Retail Experience team, you’ll help build the future of in-store technology. Your code will connect people with performance, power a seamless omnichannel journey, and support a mission that’s bigger than any one screen: to ignite the human spirit through movement.
Ready to help us redefine retail? Lace up. Let’s go.