Staff Engineer, Frontend - Domains Growth

Company Introduction   We exist to wow our customers. We know we’re doing the right thing when we hear our customers say, “How did we ever live without Coupang?” Born out of an obsession to make shopping, eating, and living easier than ever, we’re collectively disrupting the multi-billion-dollar e-commerce industry from the ground up. We are one of the fastest-growing e-commerce companies that established an unparalleled reputation for being a dominant and reliable force in South Korean commerce.    We are proud to have the best of both worlds — a startup culture with the resources of a large global public company. This fuels us to continue our growth and launch new services at the speed we have been since our inception. We are all entrepreneurs surrounded by opportunities to drive new initiatives and innovations. At our core, we are bold and ambitious people that like to get our hands dirty and make a hands-on impact. At Coupang, you will see yourself, your colleagues, your team, and the company grow every day.   Our mission to build the future of commerce is real. We push the boundaries of what’s possible to solve problems and break traditional tradeoffs. Join Coupang now to create an epic experience in this always-on, high-tech, and hyper-connected world.     Role Overview We're looking for a Senior Staff Engineer to lead the technical direction of MyCoupang, Coupang's post-purchase customer experience platform. Every order tracking, delivery, return, payment, and support interaction for tens of millions of active customers across Korea and Taiwan flows through this system.  MyCoupang operates at significant scale: ~34,000 requests per second, ~2.4 billion requests daily, and ~16 billion weekly, served by 700+ production pods with a 9x daily traffic swing that must be absorbed seamlessly. The platform delivers P95 latency under 500ms, P99 under 1 second, and maintains a 0.002% error rate. Built on Kotlin (backend), TypeScript with server-side rendering and ReactJS (frontend), the system spans a dual-service architecture with 100+ page routes and 30+ business domains including Orders, Payments, Delivery, Cancel/ Return/Exchange, WOW Membership, Travel, and Contact Center. The team ships 100+ features monthly, supports multi-market business logic across KR and TW (each with region-specific compliance, internationalization, and payment methods), and enforces security through a 4-phase authorization pipeline. This is a complex, high-stakes environment where architectural decisions have immediate customer impact. What You Will Do  In this role, you will own the most critical technical challenges on the platform: designing multi-market abstractions that scale to new regions, driving the system toward 99.99% availability, leading disaster recovery readiness and capacity planning across the full production fleet, and defining the long-term architecture for a platform that must reliably serve billions of requests weekly while continuing to evolve. You will directly influence customer retention and satisfaction metrics for every Coupang post-purchase interaction, set the engineering bar for the team, and shape the technical strategy for one of Coupang's most customer-facing systems. Basic Qualifications  * Minimum 12 years of experience working on software design and development in Java. * Hands-on experience with designing, building, and deploying scalable, high available systems * Experience with high-throughput, low-latency systems handling millions of requests * Experience with event-driven architectures using Kafka or similar messaging systems * Strong problem-solving skills and ability to debug complex distributed systems * Excellent collaboration skills to work with cross-functional teams (Product, CS, Logistics, Payment) Preferred Qualifications   * Backend development (Java, Kotlin, or similar JVM languages preferred) * RESTful API design and implementation * Database design and optimization (MySQL, * Aurora)Message queue systems * (Kafka)Workflow engines (Activiti BPMN, Temporal) * Monitoring and alerting (Grafana, CloudWatch) * Version control * (Git)CI/CD tools (CircleCI or similar   Type of work model  * Hybrid Details to consider  * Those eligible for employment protection (recipients of veteran’s benefits, the disabled, etc.) may receive preferential treatment for employment in accordance with applicable laws.    Privacy Notice   * Your personal information will be collected and managed by Coupang as stated in the Application Privacy Notice located below. https://privacy.coupang.com/en/land/jobs/

ABOUT ENGINEERING AT FONOA Engineering is central to how we build the business. We focus on solving real customer problems, not just shipping features. We work in small, high-trust teams, with full ownership across the lifecycle, from design to production and beyond. We value: * Ownership – engineers own what they build end-to-end * Simplicity – we break down complex problems into clear solutions * Thinking Big - we innovate with modern technologies (LLMs, AI Agents, etc.) to solve meaningful problems * Quality – scalable, maintainable systems are non-negotiable * Speed & iteration – we ship fast, learn, and improve continuously * Collaboration – we win as a team, not as individuals POSITION OVERVIEW As a Staff Engineer, your role is to improve the system as a whole, both technically and organizationally. You will work on ambiguous, high-impact problems, shape technical direction across teams, and help others build better systems. Your impact comes less from the code you write, and more from how you influence decisions, design, and execution at scale. WHAT YOU WILL DO * Take ownership of complex, cross-team problems that are not clearly defined * Define technical direction and drive system design across domains * Identify and address systemic issues and opportunities early * Simplify complexity through better architecture, patterns, and structure * Improve how teams build by raising standards, tooling, and practices * Mentor engineers and contribute to hiring and team growth * Ensure systems are reliable, scalable, and built for long-term evolution WHAT GOOD LOOKS LIKE * You focus on high-leverage problems and shape how they are approached * You create clarity in ambiguous situations and align teams around it * You improve not just code, but how teams design and build systems * You make others more effective through guidance, feedback, and direction * You operate with long-term thinking, balancing today’s needs with future scale * You adopt emerging AI technologies and create a culture of innovation in your teams At this level, you are expected to “make the whole system, and the people in it, better.” WHAT WE’RE LOOKING FOR * Strong experience designing and operating scalable backend systems * Proven ability to work on ambiguous, high-impact problems * Track record of influencing technical decisions beyond your team * Ability to balance speed, quality, and long-term maintainability * Experience mentoring engineers and improving team practices * Fostering a culture of curiosity and experimentation API DOCUMENTATION For engineers, API design and structure are an important part of evaluating a role. You can explore our API and how we build products here: https://docs.fonoa.com/ TECH STACK We use these technologies today, but we don’t hire for specific tools. We care about engineers who can understand problems, make good technical decisions, and choose the right tools for the job. * Backend: Node.js, Go * Frontend: React, TypeScript * Infrastructure: GCP, k8s, Terraform, Postgres Note: If you don’t think you have the full experience we’re looking for, but you could be a fit and are willing to learn, do apply anyway! We are building a diverse and inclusive team. As part of the recruitment process at Fonoa, we process your personal data in accordance with our Privacy Notice for Job Applicants. This notice explains how and why your data is collected and used, and how you can contact us if you have any concerns.