Senior Staff Engineer - Backend (Finance Platform)

Coupang

Company Introduction   We exist to wow our customers. We know we’re doing the right thing when we hear our customers say, “How did I 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 trade-offs. Join Coupang now to create an epic experience in this always-on, high-tech, and hyper-connected world.     Role Overview Fulfilment Optimization (FO) owns the systems that decide how every Coupang order is planned, distributed, and fulfilled. Our Tier-1 services sit on the critical path of Coupang's ecommerce order flow — processing every order in real time across Korea and Taiwan. We operate multiple interconnected platform components: -Business Engine — Core order planning and distribution orchestrator (Kotlin/Spring Boot). Runs 5 distinct pipelines (Domestic, Cross-Market, 3PL, PDD, Replan) using a hexagonal architecture with pluggable processors, pruners, and manifest-based orchestration. -Planner Solver — Mixed-Integer Programming (MIP) optimization engine (Python/CPLEX) that minimizes total fulfilment cost across inventory, capacity, network, and delivery-promise constraints with sub-second latency requirements. -Network Manager — Manages fulfilment network topology, transportation cost, FC capacity, middle-mile logistics, and cross-FC consolidation (CFCC) across 90+ REST/gRPC endpoints. -FO Inventory — Real-time inventory availability, allocation, SKU management, and event-driven sync across multiple upstream sources (Kafka, Cassandra, Elasticsearch, Redis). -WMS Fulfilment — Order distribution, inventory allocation, fulfilment centre orchestration, shipment, delivery, and outbound management (Java/Spring, 138+ domain subpackages, Drools rules engine). -Online Simulation — Real-time simulation platform for testing planning changes against production-like order streams. -FO Workflows — Temporal-based workflow orchestration for long-running fulfilment processes. The Role We are looking for a Senior Staff Engineer who can operate across deep implementation and broad architecture. You will set the technical direction for Tier-1 fulfilment systems, write and review production code, design systems that scale under heavy ecommerce traffic, and raise the engineering bar across the organization. The engineer in this role will directly influence how millions of orders are fulfilled every day. Every architectural decision — solver latency, pruning strategy, network cost calculation, inventory allocation algorithm impacts customer delivery promise, fulfilment cost, and operational efficiency across Coupang's entire ecommerce platform in Korea and Taiwan. This is a rare opportunity to work at the intersection of large-scale distributed systems, real-time optimization, and ecommerce fulfilment — with direct, measurable business impact. What You Will Do  -Design and build scalable, reliable Tier-1 services for order planning, fulfilment optimization, inventory allocation, and network cost management — systems that process every Coupang order in real time. -Own architecture across distributed systems involving gRPC service meshes, Kafka event pipelines, CPLEX optimization solvers, multi-layer caching (Redis, S3-backed Loadable Stores), and multi-region deployments. -Write production code in Kotlin and Java and set the bar for correctness, performance, and operational safety across the team. -Lead design and code reviews — identify correctness issues, scalability risks, and operational gaps in systems handling latency-sensitive order flows (sub-second solver deadlines, P99 monitoring with 3-5s alert thresholds). -Drive reliability for mission-critical services — circuit breakers, graceful degradation (hard/soft pruners with fallback), observability, and incident prevention. -Partner with Product, Data Science, and Operations to translate fulfilment optimization goals into technical execution — PDD rationalization, CFCC (Cross-FC Consolidation), CFlow transport planning, inventory group management, and solver model improvements. -Mentor engineers and create durable technical mechanisms (pipeline patterns, adapter abstractions, feature flag discipline) that scale beyond individual projects   Basic Qualifications -Proven experience designing and operating high-scale distributed systems with strict latency and reliability requirements -Excellent hands-on coding ability in Kotlin or Java (backend systems at scale) -Deep understanding of system design — API design, concurrency, data modelling, caching strategies, messaging, service-to-service communication (gRPC, REST) -Strong code review skills — ability to identify subtle correctness, performance, and reliability issues in complex codebases -Experience with production-grade systems handling high QPS, large data volumes, or Tier-1 SLAs -Experience with event-driven architectures using Kafka at scale -Experience with multi-region systems — region-specific routing, data isolation, cross-border fulfilment -Experience with resilience engineering — circuit breakers, retry strategies, load testing, capacity planning, graceful degradation patterns -Track record of technical leadership — setting architecture direction, driving cross-team alignment, mentoring senior engineers   Preferred Qualifications -Experience in ecommerce, fulfilment, supply chain, logistics, inventory, order management, or planning systems -Experience with optimization systems — solvers (CPLEX, OR-Tools), decision engines, constraint programming, or data-science-integrated production systems -Experience with Agentic AI tools for development and code review — using AI-assisted coding agents (e.g., Cursor, Copilot, Devin, Claude Code) to accelerate development velocity, improve code review quality, and automate repetitive engineering tasks -Experience with Spec-Driven Development — defining system behaviour through specifications (OpenAPI/Swagger, Protocol Buffers, API-first design, contract-first development) before implementation, ensuring well-defined contracts between services   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/

Coupang

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/

Coupang

Senior Staff Technical Program Manager   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. Coupang is one of the largest and fastest growing commerce platforms on the planet. We are a global company with offices in Beijing, Los Angeles, Seattle, Seoul, Shanghai, and Silicon Valley. Role Overview and What You Will Do As a Technical Program Manager, you will work closely with members of multiple business & Engineering teams to help define, streamline, design and analysis data to build business requirements and then work with engineering teams to articulate requirements, further perform functional & technical data & system analysis, drive engineering to implementation via all phases of Software Development Lifecycle (SDLC). In addition, the ideal candidate must possess a high degree of collaborative skills, and the ability to communicate effectively on many levels. Responsibilities * Strong functional & technical analytical & design capability to understand Common & shared platforms, web, & services API with underlying data. * Should be able to dive deep to come up with new Platform scenarios that help solving systems bigger problems by simplifying our services & cloud platform and help increase productivity & efficiency or every Engineer & system in the company. * Solid Platform, Web services, API technologies experience. * Strong blend of technical, business, and program management experience that enables seamless communication across teams, project execution and great customer reach. * Own, manage and deliver multiple large scale, complex programs across organizations with ease of simplicity, taking teams along to the path of success. * Own and Manage implementation E2E from Project charter, roadmap, plan, design, design, build, execute, deliver and monitor performance & adoption. * Creates, evolves, and communicates specifications for feature areas that enable cohesive, compatible, iterable scenarios that span multiple feature teams and enable a durable multi-year vision. * Should be able to come up with scenarios and business requirements by analyzing data and business needs. * Excellent cross-group collaboration and communication skills * Strong problem-solving skills, analytical capabilities, and attention to detail * Strong cultural change management experience * Identify, Propose and Implement ongoing data strategy and drive data quality improvements * Establishes, enables and improves systems to manage product feedback from customers to resolve issues. Who we are looking for (Basic Qualifications)   * Minimum of 12 Years of Engineering Program Management experience in managing feature teams and designing large-scale or complex technical initiatives on shared Platform for Web & Web services, API, Data analytics * Minimum of 5 Years in Platform, Web design, API that are used by internal & external teams. * Flexible, agile and fast learner.   Preferred * Bachelor’s degree or equivalent work experience required Outstanding verbal and written communication * Excellent cross-group collaboration and communication skills * Demonstrated virtual team leadership capabilities * Knowledge or experience agile development methodologies (i.e. Scrum).   Recruitment Process * Application Review - Phone Interview - Onsite (or Virtual Onsite) Interview – Offer * The exact nature of the recruitment process may vary according to the specific job and may be changed due to scheduling or other circumstances. * Interview schedules and the results will be informed to the applicant via the e-mail address submitted at the application stage.   Details to Consider * This job posting may be closed prior to the stated end date for application if all openings are filled. * Coupang has the right to rescind an offer of employment if a candidate is found to have submitted false information as part of the application process. * 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/