Senior Staff Backend Engineer

Coupang · Bengaluru · Posted 2026-07-18

Tech stack: Cassandra, Elasticsearch, Java, Kafka, Kotlin, Python, Redis, Spring Boot, Spring, Backend

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About the role

Responsibilities:
- 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.
- 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.
- 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
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
- 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
- Hybrid

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
- 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 Hybrid

Responsibilities

- 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.
- 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.
- 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

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