Lead javascript developer Work, Jobs (with Salaries)

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

About 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.

London

Home to nearly 3000 parks, a population speaking more than 300 languages, and a vibrant art and music scene, London is one of the world’s most loved cities for good reason.

12 Fleur De Lis Street,
E1 6DB
United Kingdom

Location

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.

Build the better you

What to expect

We want to set everyone up for success, so here’s the lowdown on how we hire. Our process is a two-way street – bringing you into our culture, while helping us learn how you think.

Our full process can last about eight weeks from application to offer, because we care about getting it right. These steps explain how we usually do things.

Before you get started, feel free to consider if you want to work with us. Strange question? Well, we give people a lot of space to navigate their day-to-day and that style isn't for everyone. We want you to be passionate about what you do and be sure this is the right fit. Because when skills and passion combine – it creates that 'Wow' moment.

Step One

It starts with you...

You'll start by submitting your application to a specific role. We try to keep this step as simple as possible. We do get a lot of applications, but we review them all. If you're a good fit to the role, a recruiter will follow up with you directly. If you didn't receive a reply, or were unsuccessful this time around, we encourage you to look for other possible matches at On.

Step Two

Interview with a recruiter

What ignites your spirit? This is where we’ll start getting to know all about you and what makes you tick – and it’s your first chance to get a feel for our culture. Chatting with a member of our talent team, you’ll learn more about On and how we work. We’ll learn about what motivates you and what you could bring to the team.

Step Three

Interview with a hiring manager

Ready to dig into the details? This second interview will be held with your future manager and will focus on the specifics of the job. Together you’ll delve into your unique skills and experiences and how they could be relevant at On. It's also a time to assess how you might feel working side-by-side. Bring any questions you have about the job, the team or anything else you might like to know – this is an open forum.

Step Four

The Case Study

What's your style? This task will help us understand how you think, face a challenge and give insight into your novel ideas. Designed to give everyone their best shot, your case study is based on something you might typically experience on the job. This is your chance to show us what you’ve got. So express yourself. Be you.

Step Five

The Experience Day

Your first taste of the Oniverse. This is a time to meet some of the people you'll be working closest with. In person or virtually, you'll get a feel for the day-to-day at On and the people who make it happen. You'll chat with a few potential teammates - the conversations will be as equally driven by the role and your experience as by our values. We believe how you do things is just as important as what you do.

Step Six

The Result

Are we a good fit? We’ll get together internally to share our feedback and decide if we’re a match. We know that job searching is a big time investment, so it’s not a decision we take lightly. It’s also time for you to reflect on the experience – are we the right place for you? No matter the outcome, we’ll give you meaningful feedback.

Apply Now

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In short

Your Mission

Your story

About the Team

London

What we offer

What to expect

Step One

It starts with you...

Step Two

Interview with a recruiter

Step Three

Interview with a hiring manager

Step Four

The Case Study

Step Five

The Experience Day

Step Six

The Result

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