On Senior Software Engineer - POS Integrations

On; City Of London; On-site; GBP 90,000 - 130,000; Full time

Job summary

On is building a future-ready POS ecosystem. We seek a backend/ integration engineer to design scalable services powering POS integrations across ERP, eCom, CRM, inventory, and loyalty.

You’ll implement REST/GraphQL APIs, real-time data flows, and secure auth patterns while embracing a cloud-native, event-driven architecture. You’ll work on testing, monitoring, and collaboration with frontend, product, and vendor teams to shape the composable commerce stack.

Qualifications

• Strong 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 (PostgreSQL) and IaC 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.

Responsibilities

• Backend & integration engineering: design, build, and scale backend services powering POS integrations across ERP, eCom, CRM, inventory, and loyalty.
• Architecture & resilience: build cloud-native, event-driven patterns with scalable messaging (Kafka) and serverless workflows.
• Testing & automation: implement contract/load tests and data pipelines; contribute to CI/CD and release confidence.
• Collaboration & strategy: align integration design with platform capabilities; influence vendor evaluations and roadmaps.

Skills

Backend engineering

API integration

Headless commerce

Kafka

PostgreSQL

Terraform

Cloud platforms

OAuth2

Telemetry

Tools

Terraform

NewRelic

OAuth2

Job description

In Short:

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.

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:

• Strong 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
  

Your Team:

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.

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.