- Large-Scale E-Commerce: Work on high-traffic, mission-critical Java platforms.
- Technical Challenges: Solve complex scalability, performance, and reliability problems.
- Technical Leadership: Drive architecture, modernization, and mentor engineers.
Senior Java Backend Engineer – E-Commerce Platform
Location
Japan – Onsite
About The Role
We are looking for a highly experienced Senior Java Backend Engineer to join an engineering team developing and operating large-scale e-commerce platforms.
You will be responsible for designing, developing, and maintaining reliable backend services that support merchant-facing business operations. The role involves working on high-traffic systems, improving performance and scalability, and delivering new features while maintaining high levels of system stability.
This is an opportunity to work on technically challenging systems and contribute across backend development, system design, performance optimization, and production operations.
Responsibilities
- Design, develop, test, and deploy scalable backend applications using Java.
- Develop and maintain RESTful APIs and business logic.
- Design and implement reliable services for high-traffic production environments.
- Improve application performance, scalability, availability, and stability.
- Participate in system architecture and technical design discussions.
- Conduct code reviews and contribute to engineering best practices.
- Investigate production incidents and perform root-cause analysis.
- Support monitoring, alerting, deployment automation, and other DevOps initiatives.
- Work closely with Product Managers, Project Managers, and other engineers.
- Contribute to system migration and platform modernization projects.
- Lead technical initiatives and mentor other engineers when required.
Required Qualifications
- 7+ years of professional Java development experience.
- Strong experience with Java frameworks and backend application development.
- 1+ year of experience working with Linux.
- Experience developing and operating high-traffic, high-availability web applications.
- Strong understanding of relational databases, particularly MySQL.
- Experience with Git, Maven, and Jenkins.
- Understanding of DevOps and/or SRE principles.
- Experience with production monitoring and troubleshooting.
- Knowledge of load testing and performance optimization.
- Experience working with containers, middleware, or production infrastructure.
Preferred Qualifications
Experience with any of the following technologies is a plus:
- Play Framework
- Hadoop
- HBase
- Apache Spark
- Couchbase
- Key-Value Stores (KVS)
- Varnish
- Apache HTTP Server
- Apache Tomcat
Additional Experience In The Following Areas Is Highly Valued
- Large-scale system migration
- New platform development
- Distributed systems
- Cloud infrastructure
- Infrastructure automation
- Performance tuning
- Production system operations
- DevOps / SRE
- Technical leadership and mentoring
Technical Environment
- Language: Java
- OS: Linux
- Database: MySQL / RDBMS
- Framework: Play Framework
- Web / Application Server: Apache, Tomcat
- Caching / Storage: Couchbase, KVS, Varnish
- Big Data: Hadoop, HBase, Apache Spark
- CI/CD: Git, Maven, Jenkins
What You'll Work On
- Large-scale merchant-facing e-commerce platforms.
- High-availability backend services.
- RESTful APIs and business-critical application logic.
- Performance and scalability optimization.
- Platform reliability and operational improvements.
- New feature development and system enhancements.
- System migration and modernization initiatives.
Team Structure
You will work in a cross-functional engineering team consisting of approximately:
- 5–6 Software Engineers
- 1 Project Manager
- 1 Product Manager
The team collaborates closely to design, develop, and operate reliable services supporting large-scale e-commerce business operations.
What Makes This Opportunity Attractive
- Work on high-traffic, mission-critical Java systems.
- Solve complex challenges around scalability, reliability, and performance.
- Take ownership of backend services from design through production operation.
- Gain experience with distributed systems and large-scale infrastructure.
- Contribute to modernization and migration initiatives.
- Work closely with product and project stakeholders.
- Opportunity to take on technical leadership and mentoring responsibilities.
Ideal Candidate
The ideal candidate is a senior backend engineer with strong Java expertise and experience working with large-scale production systems.
You are comfortable taking ownership across development, system design, troubleshooting, performance optimization, and operations, and enjoy solving complex technical problems in a high-availability environment.
Nice to Have
- DevOps or SRE experience.
- Experience operating large-scale production systems.
- Strong performance tuning and scalability optimization skills.
- Experience with distributed systems.
- Experience leading technical projects or mentoring engineers.
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