Staff Back-end Engineer

Seoul (On-site) • Full time

  • Java

The Recommendation team is responsible for Coupang’s related product recommendation, personalized gateway, widget ranking, and product review quality. Related product recommendation is a fast-growing area and we are continuously improving recommendation quality to help more and more customers find the best products for them. We have also started investing in personalized Gateway, aiming to build one of the best e-commerce discovery experiences. We use the state of the art Machine Learning and Deep Learning technologies, and we continuously innovate and build highly scalable systems to support the growing business and customer engagement.

About the Role

As a Staff Backend Engineer for Recommendations, you will be responsible for the design, development and maintenance of the end-to-end Recommendation ecosystem. This encompasses our online ranking system, multiple data pipeline that produces the candidates and features (offline and online) used across our different ranking logics, a serving system that produces content for most of Coupang app. You will need to collaborate closely with the Silicon Valley team that shares ownership of the system. In a controlled environment, run experiments to validate and launch any features that would improve the customer experience.

Key Responsibilities:

  • Own the Recommendation service, one of the most critical for Coupang to make sure we are wowing customers constantly.
  • Collaborate tightly with the Silicon Valley team to co-build a world class recommendation system
  • Knit across teams by collaborating with product managers and designers and other functions to build holistic experience that's right for Coupang users.
  • Lead each step of the product development process, from ideation to implementation to release; from rapidly prototyping, running A/B tests, to architecting and building solutions that can scale to support millions of users.
  • Contribute best-in-class programming skills to develop highly innovative consumer-facing mobile products
  • Mentor and grow engineers on the team


  • Bachelor's degree in Computer Science or Computer Engineering or electrical/electronic engineering, mathematics or equivalent
  • 5+ years of relevant industry experience with distributed systems, transactional datastores, and systems programming
  • 5+ years of solid work with fundamental algorithms, system design, and large distributed systems
  • 5+ years of coding experience in one of the following: with: C++, Java, Python, Scala
  • Experience in building and owning critical user-facing API platform and corresponding backend data systems, and solving complex design, scaling, latency, or performance problems in high-volume low-latency distributed systems
  • Strong communication skills

Preferred Qualifications:

  • Professional Korean proficiency
  • Master's degree in Computer Science or Computer Engineering or related science majors.
  • Industrial experience working with online serving system working at scale
  • Write robust and efficient code using Java with unit and integration tests
  • Experience in distributed processing using EMR, Spark, Hive, or other big data frameworks
  • Experience in Stream-processing systems (Kafka, Storm, Spark-Streaming or equivalent)
  • Excellent communicator with great listening skills, growth mindset and can-do attitude