Software Engineer, Experimentation System – Mercari, Tokyo, Japan

Job Description

Mercari is hiring a Software Engineer for its Experimentation System team in Minato City, Tokyo, Japan. This is a full-time, hybrid role based at Mercari's Roppongi office with full flextime and no core hours. The Strategic Experimentation and Analytics team runs the Experimentation Platform and Feature Flags systems that let anyone at Mercari run A/B tests and roll features out safely across production and development.

WHAT YOU'LL DO
- Continuously improve access control, resource allocation, cost optimisation and usability of the experimentation platform
- Design and maintain a scalable distributed system
- Implement new features on an existing code base
- Scale the current product to handle 10x load
- Design and implement agentic workflows for modern AI use cases

REQUIREMENTS
- Go, Python and TypeScript
- Good computer science fundamentals
- Experience with cloud technologies
- Ability to operate and debug via observability metrics and Kubernetes
- Basic familiarity with cloud databases and tools such as Google Cloud, BigQuery and Redis
- English at B2 level and above; Japanese A2 is optional

HOW TO APPLY
Apply directly on Mercari's careers page. The full job description and application route are available on the EchoJobs listing, which was pulled from Mercari's careers page and verified live on 28 September 2026:
https://echojobs.io/job/mercari-software-engineer-experimentation-system-mercari-zl04k

Responsibilities

Improve access control, resource allocation, cost optimisation and usability of the experimentation platform; design and maintain a scalable distributed system; implement new features on an existing code base; scale the product to handle 10x load; design and implement agentic workflows.

Requirements

Go, Python and TypeScript; good computer science fundamentals; experience with cloud technologies; observability and Kubernetes debugging skills; familiarity with Google Cloud, BigQuery and Redis; English B2 and above; Japanese A2 optional.

Benefits

Full flextime with no core hours; hybrid working from the Roppongi office.