Senior Java Backend Engineer – Global E-Commerce

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 availabilityDistributed systemsPerformance optimizationDatabase efficiencyResilient microservice architecturesHigh-volume APIs and transactionsProduction 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 architectureTechnical design and specificationsAPI and database designTechnology selectionPerformance and scalability improvementsProduction troubleshootingCode reviews and engineering standardsTechnical 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 servicesDesign and implement scalable RESTful APIs and microservicesDefine technical specifications and contribute to architecture documentationDesign and optimize database schemas, queries, and data access patternsDevelop automated unit, integration, and end-to-end testsParticipate in code reviews and technical design discussionsCollaborate with engineers, produc