Staff Backend Engineer – Fulfilment Optimization

About the role

Coupang is looking for a Staff Backend Engineer to lead the design and operation of Tier‑1 fulfilment systems that process every order in real time across Korea and Taiwan. You will shape technical direction, write production‑grade code, and influence how millions of orders are fulfilled daily.

Key responsibilities

• Design and build scalable, reliable services for order planning, optimisation, inventory allocation and network cost management.
• Own architecture across gRPC service meshes, Kafka pipelines, CPLEX solvers, multi‑layer caching and multi‑region deployments.
• Write production code in Kotlin and Java, set standards for correctness, performance and safety.
• Lead design and code reviews, identifying correctness, scalability and reliability risks.
• Drive reliability through circuit breakers, graceful degradation, observability and incident prevention.
• Collaborate with Product, Data Science and Operations to translate optimisation goals into technical execution.
• Mentor engineers and create reusable technical mechanisms that scale beyond individual projects.

Required profile

• Proven experience designing and operating high‑scale distributed systems with strict latency and reliability requirements.
• Excellent hands‑on coding ability in Kotlin or Java for backend systems at scale.
• Deep understanding of API design, concurrency, data modelling, caching strategies and service‑to‑service communication (gRPC, REST).
• Strong code‑review skills to spot subtle correctness, performance and reliability issues.
• Experience with high QPS, large data volumes or Tier‑1 SLAs and event‑driven architectures using Kafka.
• Experience with multi‑region systems, resilience engineering (circuit breakers, retries, load testing) and capacity planning.
• Track record of technical leadership, setting architecture direction and mentoring senior engineers.

Required skills

• Kotlin
• Java
• Spring Boot
• gRPC
• Kafka
• CPLEX
• Python
• Redis
• Cassandra
• Elasticsearch
• S3
• Drools
• Temporal
• REST
• OpenAPI/Swagger
• Protocol Buffers