Staff Engineer, Seller Systems

HI, WE’RE BACK MARKET. We’re here to help make tech reliable, affordable, and better than new. We're a global marketplace for refurbished devices, helping lower our collective environmental impact by providing trustworthy, affordable tech with 92% less carbon emissions than new. Yep, you read that right. Turns out refurbished tech is way better for the planet than new. In fact, With every device purchased on Back Market, our positive impact on the planet grows. From our Customer Care representatives to our software engineer, every individual at Back Market cuts the planet — and consumers — a break. Our mission is simple: to do more with what we already have. Are you ready to join us? Our technology department, known as the Bureau of Technology (BoT), is at the heart of Back Market. It consists of over 30 dynamic product teams that are engaged in developing and managing services to deliver significant value to our customers and suppliers. These teams are effectively supported by our Platform group, which includes more than 10 specialized teams addressing cross-cutting technical issues to enhance our operational capabilities. In addition to these functional teams, we have established numerous groups dedicated to sharing knowledge across various technical disciplines, such as security, backend, frontend, AI, and mobile. These groups serve as hubs for collaboration and professional development, providing ample learning opportunities and fostering a culture of continuous improvement. Seller Experience team's mission: Help sellers to be more efficient ! As a Software Engineer, you will work closely with all members of your squad, and the Staff engineer of your group. Bi-monthly rituals with your group and the Chapter will allow you to share what works for your squad, learn what works for others, and make sure your technical direction is aligned with the overall vision. What you will do in this role We’re looking for versatile engineers who show strong ownership and are motivated to take on new challenges across the technical stack while helping us move our technology forward.   You will be working in an agile "build it and run it" environment where engineering teams build, launch, monitor and support the product that they own. Driven by the desire to craft outstanding products, you understand how to deliver seamless user experiences at scale. We are looking for passion in creating systems by producing clean, consistent and well-organized code. As well as a good team player supporting colleagues and creating a learning and sharing environment! English must be a no-brainer as you will join an international team dispatched in different locations around the world (US/FR/ES/JP). Technical environmentOur platform is based on Nuxt/Vue.js and our own Design System. We love TypeScript, our design tokens and Tailwind are in a bromance, and we do our best to be accessible to anyone. Everything is Server Side Rendered, and served through Node.js, Cloudflare CDN and Cloudflare Workers. Our GitHub contributions go through CircleCI, to be fully tested by Vitest, the Testing Library and Playwright. We release and deploy in production multiple times a day. Required profile : * You have already worked on projects based on Vuejs, React or Angular. * You have significant experience with web technologies such as Javascript, NodeJS, HTML 5 and CSS. * Quality of code is your priority and you follow best practices. * Scrum and kanban are not karate katas and you hate the V-cycle. * You are comfortable working both in a team and also working independently to ensure goals are achieved.  * You have the ability to foresee where your interfaces may need to be altered to keep in line with the company strategy. * You want to join a challenging technical environment: GCP, Kubernetes, Docker, RestFul API, Python, Django, VueJs, Nuxt, Algolia, Datadog, Spinnaker, SQS, ElasticSearch, Nginx, UWSGI. Bonus Skills : * You understand the back-end constraints and can design an API call. * You're good at finding cool names. * You have experience with Single Page Applications served in Server Side Rendering such as Nuxt/Next * You've already tried TypeScript, Flow, etc... * Monitoring is second nature * Software craftsmanship & clean code are in your library Recruitment process :  * Call with one of our Tech talent acquisition manager - 45 min  * Technical screening with 2 frontend engineers 45 min  * Technical Interview & Technical Leadership Interview with 2 members of the tech team - 90min * Coffee chat with your future engineering manager - 30 min  * Back Market values interview with 2 members of the Exec level - 45min WHY SHOULD YOU JOIN US ? ✌🏼 At Back Market, we’re committed to hiring and supporting diverse teams of people from all backgrounds, experiences, and perspectives — it’s one of the reasons we’re such a high-scoring certified B Corp company (93.2). No matter your role and seniority level, you’ll enjoy impact-driven work with hands-on career development in an innovative, driven, and fast-paced environment — with benefits to match, like:  - A mission driven work environment where your day to day makes an impact on the planet. Seriously. - Hybrid work environment, with 2 remote days a week and 1 remote work week per quarter, plus 3 flex days.  - Employee Resource Groups, including mentorship programs, comprehensive accessibility policies, and cultural competency training.  At Back Market, we strive to create a workplace that embodies the world we’re trying to change. We’ve embedded our diversity, equity, and inclusion principles into our DNA — from dedicated staff to employee resource groups to our company values.  We know that the perfect background for a role doesn’t mean the perfect fit — we encourage you to apply for a role even if you think you may not have all the qualifications.  If reasonable accommodations are needed for the interview process, please do not hesitate to discuss this with the Talent Acquisition Team. WHY SHOULD YOU JOIN US ? ✌🏼 At Back Market, we’re committed to hiring and supporting diverse teams of people from all backgrounds, experiences, and perspectives — it’s one of the reasons we’re such a high-scoring certified B Corp company (93.2). No matter your role and seniority level, you’ll enjoy impact-driven work with hands-on career development in an innovative, driven, and fast-paced environment — with benefits to match, like: - A mission driven work environment where your day to day makes an impact on the planet. Seriously. - Hybrid work environment, with 2 remote days a week and 1 remote work week per quarter, plus 3 flex days. - Employee Resource Groups, including mentorship programs, comprehensive accessibility policies, and cultural competency training. At Back Market, we strive to create a workplace that embodies the world we’re trying to change. We’ve embedded our diversity, equity, and inclusion principles into our DNA — from dedicated staff to employee resource groups to our company values. We know that the perfect background for a role doesn’t mean the perfect fit — we encourage you to apply for a role even if you think you may not have all the qualifications. If reasonable accommodations are needed for the interview process, please do not hesitate to discuss this with the Talent Acquisition Team.

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 The Commerce Risk Detection Systems (CRDs) team focuses on seller and buyer fraud detection and prevention across Coupang’s ecosystem. The team builds large-scale, real-time systems that analyze tens of millions of commerce events daily (orders, returns, listings) to identify fraudulent behavior and patterns. A Staff Backend Engineer will operate as a technical leader, driving architecture, scalability, and innovation in fraud detection systems. The team is actively evolving from rule-based systems toward ML-driven and LLM-powered detection mechanisms for future scalability. What You Will Do * Act as a technical leader translating business fraud prevention goals into scalable technical solutions and architecture * Design and build large-scale, low-latency backend systems processing tens of millions of events per day * Develop and optimize real-time fraud detection systems using streaming data and inference pipelines * Collaborate across stakeholders including Product, Data Science, ML engineers, and leadership * Drive architectural decisions for scalable fraud detection (counterfeit detection, seller fraud, risk signals) * Evaluate and implement ML and emerging LLM-based approaches for fraud detection use cases * Advocate engineering excellence, including system efficiency, scalability, maintainability, and fault tolerance * Guide best practices and act as a role model for strong engineering standards across the team Basic Qualifications * 10–12 years of backend engineering experience  * Strong experience building large-scale, real-time distributed systems * Hands-on experience with data streaming technologies (e.g., Apache Flink or similar) * Strong proficiency in Java-based backend development * Experience designing and building low-latency, high-throughput systems * Experience working with OLTP databases in production environments * Experience building or supporting real-time inference systems (ML or rule-based) * Familiarity with using GenAI/LLM tools for engineering productivity (e.g., coding, debugging, development workflows) * Strong knowledge of system design, scalability, and fault tolerance * Strong problem-solving skills with focus on efficiency and optimal solution PREFERRED QUALIFICATIONS * Experience in fraud detection, risk systems, payments risk, or similar domains * Familiarity with commerce or fintech ecosystems (e.g., payments, marketplaces) * Experience with Apache Flink or similar streaming frameworks * Experience with OLTP databases and backend system design * Exposure to ML systems, feature stores, or inference pipelines * Familiarity with leveraging GenAI tools (e.g., code generation, debugging, productivity enhancements) * Exposure to using existing LLMs or AI assistants in engineering workflows (not model-building, but practical usage) * Proficiency in Java-based backend development Type of work model * Hybrid / Onsite / Remote working Our Hybrid work model: Coupang hybrid work model is designed to enable a culture of collaboration that acts a catalyst to enrich the experience of employees. Employees are required to work at least 3 days in the office per week, with the flexibility to work from home 2 days a week, depending on the role requirement. Some businesses may require more time in office due to nature of work. 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/l and/jobs/