API Engineer (Rakuten楽天) (#050)

Rakuten, Inc. is a Japanese electronic commerce and Internet company based in Tokyo. Among various other operations its B2B2C e-commerce platform Rakuten Ichiba is the largest e-commerce site in Japan and among the world's largest.

Position: API Engineer

※Job Requirements

  • Experience in Microservice/RESTful API Design and Development with Java/Java EE (5 + years)
  • Deep knowledge of Java Virtual Machine and GC (Class loading, Memory Management (GC tuning), InvokeDynamic… etc.)
  • Object-oriented design and analysis (GoF design pattern, SOLID principle, functional programming design)
  • Java Application Server Experience (Apache Tomcat/Grassfish/Undertow/Jetty/WebLogic… etc)
  • Deep knowledge of the Spring Framework
  • Research and operating experience on Linux
    *Software Configuration Management (Version Control [Git], Dependent Library Management [Maven, Gradle])
  • Development and Maintenance of Unit Tests (JUnit, TestNG, Mockit, JMockit, PowerMock)
  • Coding and review experience for performance, serviceability, and security


  • Enterprise development experience with SpringBoot
  • Experience in developing and operating distributed cache solutions (Redis, Memcached… etc)
  • GraphQL/JSON RPC API development experience
  • Understanding Various Authentication and Authorization Protocols (OAuth2, OpenID)
  • Experience in load testing using Apache JMeter, etc., and performance analysis and improvement
  • Docker and Orchestration Tools Experience
  • DevOps Experience with CI/CD Using Jenkins/git
  • Experience in both waterfall and agile development
  • Management experience of the development team

Position: API Development Engineer

※Job Requirements

  • Java EE: 5 + years of development experience
  • Spring Framework Development Experience
  • Experience developing RESTful Web APIs
  • Experience in design, development, and performance tuning of RDB (Oracle, Mysql, etc) databases
  • Experience in operating large-scale online systems and dealing with failures
  • Expertise in the software development lifecycle. Code standards, code reviews, source code management, build processes, testing, operations, etc.


  • Experience in design and development using KVS/NoSQL
  • Experience in developing automation tools such as Jenkins and Ansible
  • Test Driven Development experience
  • Those who have a long-term, bird’s-eye view and can choose the best course of action from time to time.
  • Can voluntarily design and develop high performance, reliable, and maintainable code

Position: API Engineer

※Job Requirements

  • Java development experience (over 7 years)
  • RESTful API development experience
  • Development experience with modem Framework such as Play framework and Spring Boot
  • Experience of using NoSQL (Apache Cassandra, Couchbase, etc.)
  • Experience of using In-Memory Cache Technology (Redis etc.)


  • E-Commerce business knowledge (B2B, B2C)
  • Experience of development and operation of large scale system
  • Experience in using API documentation tool (Swagger)
  • Development experience with Agile Scrum
  • CI / CD development cycle
  • Implementation of TESCode by Unit test / TDD
  • Promotion of automation, implementation experience
  • Code reading and contribution of open source software

Location :

Salary :
6M JPY upwards

Japanese and English (Business Level)
Also open to candidates not residing in Japan


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