On Lead Backend Engineer – POS Platforms Integration

On; Greater London; On-site; GBP 60,000 - 80,000; Full time

Job summary

A leading tech company in Greater London seeks a Backend Engineer to integrate its POS platform with key systems such as ERP and CRM. The role focuses on designing resilient backend services, developing REST and GraphQL APIs, and contributing to a cloud-native architecture. Candidates should have 3+ years of experience with modern technologies, strong skills in API integration, and familiarity with asynchronous data processing. Join a team that crafts impactful retail experiences and values your personal growth.

Benefits

Supportive and team-oriented atmosphere

Access to personal self-care programs

Qualifications

• 3+ years of backend engineering experience with modern technologies.
• Proven track record integrating APIs across commerce, ERP, OMS, or CRM domains.
• Solid understanding of databases and infrastructure-as-code tools.

Responsibilities

• Design and build backend services that power POS integrations across multiple platforms.
• Contribute to the design of a cloud-native architecture for global retail operations.
• Ensure reliability through a robust automated testing stack.

Skills

Node.js

TypeScript

APIs integration

Microservices

Asynchronous data processing

PostgreSQL

Terraform

Cloud platforms (AWS, GCP, or Azure)

Tools

Kafka

RabbitMQ

New Relic

Job description

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., New Relic).
• 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.

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.