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Senior Java Engineer - Own High-Traffic Checkout APIs (Tokyo)

Tokyo 23 Wards Temporary ¥6,000,000 - ¥8,000,000 per year Foreign Multinational View Job Description
Join a backend-focused team responsible for critical checkout services, including order data creation and cart data persistence. You will lead design through operations for high-traffic Java-based APIs, consumers, and batch systems that power a large online marketplace.
  • Build mission-critical checkout systems at massive scale
  • Long-term contract with senior ownership and technical leadership

About Our Client

Our client is a major Japan-based e-commerce marketplace operating large-scale online transaction platforms. The organization runs high-availability, high-throughput checkout and cart systems where reliability, ownership, and operational excellence are essential.

Job Description

  • Lead basic design (high-level design) aligned with business requirements for checkout-related backend services
  • Design, develop, test, and release RESTful Web APIs and supporting services (Consumer / Batch)
  • Own production operations, including monitoring, incident response, root-cause analysis, and troubleshooting
  • Drive engineering best practices across the SDLC: coding standards, code reviews, source control, build pipelines, testing, and release management
  • Collaborate proactively with Product and QA to clarify requirements, manage quality, and ensure smooth delivery
  • Provide senior-level guidance and leadership to other engineers, improving maintainability, performance, and reliability
  • Continuously enhance system stability and technical debt management in a mission-critical domain (checkout/cart)



The Successful Applicant

Must-have

  • 5+ years of Java EE development experience (senior/full-stack engineering background)
  • Hands-on experience building and operating RESTful APIs
  • Experience supporting large-scale online systems, including production incident handling
  • Strong SDLC expertise: code standards, reviews, source management, build processes, testing, operations
  • Proven ability to design and deliver high-performance, reliable, maintainable code autonomously
  • Senior-level leadership: proactive communication with QA/Product, and ability to lead projects/engineers

Nice-to-have

  • Data design/development experience with RDB / KVS / NoSQL
  • Spring Framework experience
  • Containerization experience (e.g., Docker)
  • Experience with CI/CD, and observability tools (e.g., Grafana)
  • Interest or experience using AI to improve the development lifecycle (e.g., productivity, quality, automation)


Language

  • Japanese: Not required
  • English: Conversational level (e.g., TOEIC ~600 equivalent)

What's on Offer

  • Work on one of the most critical domains in e-commerce: checkout/cart, where impact is immediate and measurable
  • High ownership role with exposure to design, delivery, and production operations end-to-end
  • Collaborative environment with cross-functional stakeholders (Product/QA/Engineering)



Contact
Serena Wu
Quote job ref
JN-052026-7019832
Phone number
+81 3 6627 6137

Job summary

Function
IT
Specialisation
Programming / Development
Specialisation
Technology & Telecoms
Location
Tokyo 23 Wards
Job Type
Temporary
Consultant name
Serena Wu
Consultant phone
+81 3 6627 6137
Job Reference
JN-052026-7019832
Company Type
Foreign Multinational

Diversity & Inclusion at Michael Page

We don't just accept difference - we celebrate it. We encourage applicants from all backgrounds to apply for this role and are committed to building inclusive, diverse workplaces where everyone can thrive. If you require any support or reasonable adjustments during the recruitment process, please let us know.