Staff Backend Engineer

Company Introduction

We exist to wow our customers. We know were 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 were 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 whats possible to solve problems and break traditional 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 Coupangs 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 Staff Engineer who can operate across deep implementation and broad architecture. You will help us enable the 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 impactscustomer delivery promise fulfilment cost and operational efficiency across Coupangs entire ecommerce platformin Korea and Taiwan.
This is a rare opportunity to work at the intersection of large-scale distributed systems real-time optimization andecommerce fulfilment with direct measurable business impact.

What You Will Do

-Design and build scalable reliable Tier-1 services for order planning fulfilment optimization inventoryallocation 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 CPLEXoptimization 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 safetyacross the team.
-Lead design and code reviews identify correctness issues scalability risks and operational gaps in systemshandling 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 withfallback) 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 flagdiscipline) that scale beyond individual projects

Basic Qualifications

-10 years of 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 messagingservice-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 planninggraceful degradation patterns
-Track record of technical leadership setting architecture direction driving cross-team alignment mentoringsenior engineers

Preferred Qualifications

-Experience in ecommerce fulfilment supply chain logistics inventory order management or planningsystems
-Experience with optimization systems solvers (CPLEX OR-Tools) decision engines constraint programming ordata-science-integrated production systems
-Experience with Agentic AI tools for development and code review using AI-assisted coding agents ( Copilot Devin Claude Code) to accelerate development velocity improve code review quality andautomate repetitive engineering tasks
-Experience with Spec-Driven Development defining system behaviour through specifications(OpenAPI/Swagger Protocol Buffers API-first design contract-first development) before implementationensuring well-defined contracts between services

Type of work model

• Hybrid

Details to consider

• Those eligible for employment protection (recipients of veterans 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. Experience:

  Staff IC