- Build and scale commerce platforms used by millions of customers, tackling real-world challenges in scalability, performance.
- Collaborate with global teams and take ownership of architecture and technical decisions.
- Modern Technology — Work with Java 21, Spring Boot 3.x, Kubernetes, Kafka, and cloud technologies.
Senior Backend Engineer in Japan (Java)
Build the Backend Systems Powering Large-Scale Commerce A leading e-commerce company is looking for a Senior Backend Engineer (Java) to join a high-performing engineering team responsible for building and scaling mission-critical commerce platforms used by millions of customers.
This is an opportunity to work on high-traffic, business-critical systems while solving challenging engineering problems across scalability, performance, reliability, and distributed systems.
The successful candidate will work closely with experienced engineers, product stakeholders, and global teams, contributing not only to implementation but also to architecture, technical decision-making, and continuous improvement.
If you are a backend engineer who enjoys taking ownership of complex systems and wants to make an impact at significant scale, this role offers an excellent opportunity to take your career to the next level.
Why This Opportunity?
Work at Meaningful Scale The systems supported by this team serve millions of users and play a critical role in the company's commerce operations.
This Means You Will Encounter Real Engineering Challenges Around
- Scalability and high availability
- Distributed systems
- Performance optimization
- Database efficiency
- Resilient microservice architectures
- High-volume APIs and transactions
- Production reliability
Your technical decisions will have a direct impact on systems used by a large customer base.
Modern Java and Cloud-Native Technologies
This team works with a modern technology stack centered around Java 21 and Spring Boot 3.x, alongside cloud-native and distributed-system technologies.
You Will Have The Opportunity To Work With
Java 21, Spring Boot 3.x, Spring Cloud, Kubernetes, Docker, Kafka, Redis, MySQL/PostgreSQL, and AWS/Azure/GCP.
This is an environment where engineers can deepen their expertise in modern backend architecture rather than simply maintaining legacy systems.
Significant Technical Ownership
As a Senior Backend Engineer, you will have the opportunity to contribute beyond day-to-day implementation.
You Will Be Involved In
- System and service architecture
- Technical design and specifications
- API and database design
- Technology selection
- Performance and scalability improvements
- Production troubleshooting
- Code reviews and engineering standards
- Technical mentoring and knowledge sharing
The team values engineers who can take ownership, identify problems proactively, and turn technical challenges into practical solutions.
Global Engineering Environment The team operates in a global and multicultural environment, collaborating with engineers and stakeholders across different locations.
This provides an opportunity to work on technically challenging projects while developing your ability to communicate, collaborate, and influence within an international engineering organization.
AI-Assisted Engineering The organization is also embracing modern AI-assisted engineering practices.
AI-powered tools are being incorporated into areas such as development, testing, documentation, investigation, and code review, helping engineers improve productivity and spend more time on high-value technical challenges.
Key Responsibilities
As a Senior Backend Engineer, You Will
- Design, develop, test, and maintain backend applications and services
- Design and implement scalable RESTful APIs and microservices
- Define technical specifications and contribute to architecture documentation
- Design and optimize database schemas, queries, and data access patterns
- Develop automated unit, integration, and end-to-end tests
- Participate in code reviews and technical design discussions
- Collaborate with engineers, product stakeholders, and cross-functional teams
- Monitor and improve system performance, reliability, and availability
- Investigate and troubleshoot production issues
- Drive continuous improvements to systems and development processes
- Identify and address technical debt
- Provide technical guidance and mentorship to other engineers
Experience
Required Qualifications
- 5+ years of professional backend software development experience
- Experience developing and operating production systems at scale
Technical Skills
- Strong proficiency in Java and object-oriented design
- Hands-on experience with Spring Boot, Spring Data JPA, Spring Security, and related technologies
- Proven experience designing and developing RESTful APIs
- Understanding of microservices architecture and distributed systems
- Strong database design and optimization experience
- Experience with MySQL and/or PostgreSQL
- Experience with JPA/Hibernate, MyBatis, or similar persistence technologies
- Experience with Git-based development workflows
- Familiarity with CI/CD pipelines and DevOps practices
- Experience with AWS, Azure, or Google Cloud Platform
- Experience with Docker and containerized environments
Soft Skills
- Strong problem-solving and analytical abilities
- Self-driven and proactive approach to engineering
- Strong sense of ownership and accountability
- Ability to communicate effectively with technical and non-technical stakeholders
- Ability to collaborate effectively in a global, cross-functional environment
Language
- Business-level English or above
Preferred Qualifications The following experience would be highly valued:
- Experience building e-commerce or consumer-facing platforms
- Production experience with Kubernetes
- Experience with Kafka, RabbitMQ, or event-driven architectures
- Experience with Redis and distributed caching
- Knowledge of cloud-native architecture and SRE practices
- Experience with application, database, or JVM performance tuning
- Experience designing and operating large-scale systems handling significant traffic volumes
- Experience mentoring engineers or leading technical initiatives
- Experience contributing to architecture decisions or technical strategy
Technology Stack
Backend: Java 21, Spring Boot 3.x, Spring Cloud
Architecture: Microservices, Distributed Systems
Database: MySQL, PostgreSQL
Persistence: JPA, Hibernate, MyBatis
Messaging: Kafka, RabbitMQ
Caching: Redis
Cloud: AWS, Azure, GCP
Containers: Docker, Kubernetes
Development: Git, CI/CD, AI-assisted engineering
What Makes This Role Attractive?
This position is particularly well suited to an engineer who wants to move beyond feature development and take greater ownership of architecture, scalability, reliability, and technical direction.
You Will Have The Opportunity To
- Work on systems used by millions of customers
- Solve complex backend and distributed-systems challenges
- Build and evolve cloud-native microservices
- Work with a modern Java technology stack
- Influence architecture and technical decisions
- Collaborate with engineers across a global organization
- Develop expertise in performance, scalability, and reliability
- Mentor other engineers and contribute to technical leadership
This is a strong opportunity for engineers looking to grow toward
Tech Lead, Staff Engineer, or Architect responsibilities.
Location
Tokyo, Japan
Take the Next Step in Your Backend Engineering Career
If you are passionate about building scalable backend systems and want to work on technology that operates at significant scale, this role offers the opportunity to take on meaningful technical challenges and make a measurable impact.
Join this team and help shape the backend architecture behind a large-scale commerce platform.
TEKsystems