Web Application and Backend Engineer - Business Support Development Department (BSD)

Job Description: Business Overview We are the development department that supports Rakuten's founding business, Rakuten Ichiba. Rakuten Group, Inc. is founded in 1997 and continuing to this day, embodies Rakuten's mission of empowering people and society through innovation, and has created a system that allows people to easily open stores beyond the limits of the business sphere, delivering the joy of shopping to users throughout Japan. We are now one of the largest EC companies in Japan. Rakuten Ichiba service page https://www.rakuten.co.jp/ Department Overview Rakuten Ichiba is a place where various merchants gather, and its diversity is what makes Rakuten Ichiba attractive. Our department is responsible for developing and providing tools and services necessary for the operation of each merchant, regardless of their genre, industry, or size, in order to enable the diverse merchants on Rakuten Ichiba to thrive in e-commerce and provide customers with the experience of "Shopping is Entertainment". We are the development team behind Japan's No.1 Order Management System (OMS) by merchant count. Our work directly empowers thousands of merchants and shapes the future of online retail. Our mission is to provide merchants with a comprehensive, reliable, and efficient OMS that simplifies operations, streamline the shipping process, and drives business growth, leveraging our unique position within the Rakuten ecosystem. We began by optimizing day-to-day operations for Rakuten Ichiba merchants utilizing Rakuten's fulfillment services, building a deep foundation within the ecosystem. Recognizing a broader need, we expanded our functionalities to support all major e-commerce Malls in Japan (Amazon, Yahoo, auPAY Market, Shopify, etc.) and diverse warehousing solutions. This strategic evolution led us to become the No.1 OMS in Japan. We don't just build software, we build the critical infrastructure that allows merchants to thrive, processing millions of orders annually. Position: Why We Hire As our platform continues to evolve and we explore new functionalities within the Rakuten ecosystem and beyond, we're expanding our engineering team to accelerate our product roadmap. We're looking for talented Applications Engineers to contribute to exciting new features and scale our robust system to meet growing merchant demands. 　 Position Details Role Overview We are seeking a highly skilled and motivated C# Web Application and Backend Engineer to join one of our agile scrum teams. This pivotal role is driven by the significant growth in our user base, coupled with ambitious plans for system re-architecture and cloud migration. You will be instrumental in evolving Japan's No. 1 Order Management System (OMS), directly impacting thousands of merchants and shaping the future of e-commerce operations. This is a unique opportunity to contribute to a critical, high-volume platform within the dynamic Rakuten ecosystem. Detailed Responsibilities As a C# Web Application and Backend Engineer, your primary focus will be on designing, developing, and maintaining robust, scalable, and high-performance solutions for our core OMS. This involves working across the full stack, with a strong emphasis on backend services and API development. Your day-to-day will be dynamic and challenging, encompassing: - Solution Proposing & Design: Collaborating closely with Product Managers and fellow engineers, you will actively propose technical solutions and design new features that align directly with evolving business needs. This includes defining API contracts, database schemas, and service architectures for complex functionalities. - New Function Development: Hands-on development of new features for both our web application front-end (using modern C# web frameworks) and, more significantly, the backend services (APIs, microservices, data processing). This will involve writing clean, efficient, and well-tested C# code. - System Modernization & Re-architecture: Playing a key role in our ongoing system re-architecture efforts, including migrating existing functionalities to cloud-native solutions (e.g., Azure or AWS) and refactoring legacy components to enhance scalability, reliability, and maintainability. - Performance Optimization & Refactoring: Proactively identifying and addressing performance bottlenecks, security vulnerabilities, and code quality issues. You will be responsible for refactoring existing functions to improve their efficiency, readability, and adherence to best practices. - Troubleshooting & Support: Assisting the team in diagnosing and resolving production issues, handling inquiries, and providing technical support when needed, ensuring the continuous operation of our mission-critical system. Role Complexity & Scope of Responsibility This role presents a high level of technical complexity and significant responsibility. You will be working on a system that handles millions of orders annually, directly impacting merchant revenue and customer satisfaction. The challenges include: - High-Volume Processing: Ensuring the system remains performant and reliable under immense transaction loads, especially during peak sales periods. - System Re-architecture & Cloud Migration: Navigating the complexities of transitioning a mature, mission-critical system to a modern, cloud-native architecture. - Integration Complexity: Working with numerous external integrations (e-commerce malls, shipping carriers, payment gateways) that demand robust error handling and data consistency. - Data Integrity: Maintaining the highest standards of data accuracy and consistency across various interconnected systems. - Ownership: You will have direct ownership over the design, implementation, and quality of features, from conception to deployment, and be accountable for their performance and stability in production. Rewards & Appeal of the Role - Direct Impact: Your code will directly empower thousands of merchants, streamlining their operations and contributing to their business growth within Japan's largest e-commerce ecosystem. - Technical Challenge: Engage with complex architectural problems, high-volume transactions, and cutting-edge cloud technologies (e.g., microservices, CI/CD, multi-cluster, multi-DC). - Growth & Learning: Be at the forefront of a major system re-architecture and cloud migration, gaining invaluable experience in modernizing a critical enterprise system. - Diverse & Collaborative Environment: Work within a truly global team of engineers from 15+ countries, fostering continuous learning and diverse perspectives. Our positive and supportive culture ensures that, despite high expectations, team members genuinely enjoy their work. - Strategic Importance: Contribute to a platform that is central to Rakuten's e-commerce strategy and holds the No. 1 market share in Japan. Key Stakeholders You will regularly collaborate with: - Product Managers: To understand business requirements and define feature specifications. - Fellow Engineers (Frontend, Backend, QA): For design discussions, code reviews, and cross-functional development. - DevOps/SRE Teams: For deployment strategies, monitoring, and infrastructure support. - Business Operations Teams: To understand merchant pain points and provide technical insights. - Rakuten Group Internal Teams: For integrations and strategic alignment within the broader Rakuten ecosystem. Work Approach & Methodology We operate within an hybrid framework based mostly on Agile/Scrum framework, emphasizing iterative development, continuous integration, and frequent communication. You will participate in daily stand-ups, sprint planning, retrospectives, and regular code reviews. We value collaborative problem-solving and a proactive approach to identifying and addressing technical debt. English Usage English is the primary language of communication within our diverse engineering team. All technical discussions, daily stand-ups, sprint meetings, documentation, and code comments are conducted in English. While some communication with internal Rakuten stakeholders may involve Japanese, strong English proficiency is essential for day-to-day team collaboration and technical work. Mentor/Coach & Knowledge Sharing - Mentorship: For more experienced candidates, there will be opportunities to mentor and coach junior team members, fostering their growth and contributing to the overall technical strength of the team. - Knowledge Sharing: We believe in continuous learning. You will be expected to actively participate in knowledge sharing through discussions, technical sessions, brown bags, and contributing to our internal documentation, enriching our collective expertise. 　 Work Environment Our group is composed of a dedicated Product Management (PDM) Team (4 members) and our larger Development Team (20+ members), where this role resides. The Development Team is a vibrant hub of talent, comprising around 85% non-Japanese members from over 15 countries. This rich tapestry of cultural and professional backgrounds is a cornerstone of our innovation, bringing diverse perspectives and problem-solving approaches to every challenge. We are structured into three distinct scrum teams, each specializing in a different domain of knowledge within our OMS. Each team typically consists of 7-9 members, with a balanced mix of experience levels. This includes seasoned engineers who bring deep architectural understanding and mentorship, alongside passionate mid-career professionals and emerging talent, all contributing to our collective success. - Languages: C# (5+ years, .NET 6+), T/SQL - Backend Frameworks: ASP.NET Web API, MVC.NET, .NET Framework, .NET Core - Frontend: JavaScript, HTML, CSS, Vue.js - Databases: MS SQL Server (Primary), MariaDB, MySQL, Entity Framework, Dapper - Cloud: Rakuten's proprietary cloud - CI/CD: TeamCity, Octopus, Jenkins, Kubernetes, Docker, GitHub Actions - Messaging: Service Bus, RabbitMQ (Rebus, NServiceBus, MassTransit) - Architecture: Microservices - Big Data: Kafka or other stream processing frameworks Mandatory Qualifications: To succeed in this role, candidates must demonstrate proficiency and experience in the following areas: Basics - Strong understanding of IT fundamentals and the software development lifecycle. - Proven analytical skills and a commitment to writing clean, efficient code. - Detailed technical knowledge and development experience in web security and personal information data protection. - Experience in developing and maintaining mission-critical systems handling a high volume of daily transactions. - Practical experience in post-development system management and operation. Application Development - 5+ years of hands-on experience in C#, with a particular focus on WebAPI development. - Consistent application of SOLID principles in software design and development. - Expertise in backend development using MVC.NET, .NET Framework, or .NET Core. - Proficiency with .NET 6 or higher. - Good working knowledge of JavaScript, HTML, and CSS. - Experience in the design, development, and deployment of applications within a cloud environment, specifically experience with at least one leading public cloud platform (e.g., AWS, Azure, GCP). Database - Good understanding and working experience with ORMs such as Entity Framework and Dapper. - Proficiency in T/SQL with a focus on MS SQL Server. Soft Skills - Demonstrated ability to be a proactive team player. - Excellent communication skills. - Ability to mentor and coach other team members. - Possession of an Agile mindset and the capacity for innovative, "out-of-the-box" thinking. Desired Qualifications: While not strictly mandatory, candidates possessing the following skills and experiences will be highly regarded: - Experience with CI/CD configuration and deployment using tools such as TeamCity, Octopus, Jenkins, Kubernetes, Docker, or GitHub Actions. - Familiarity with Messaging Systems and Patterns, including Service Bus/RabbitMQ with Rebus/NServiceBus/MassTransit. - Good working knowledge of Microservices architecture and development. - Experience with MariaDB or MySQL. - Working experience with Kafka or any other big data stream processing framework. - Experience in developing systems implementing the Scrum Methodology. - Prior experience working effectively with multi-cultural and multi-generational teams. - Experience in a Scrum Master role. 　 Other Information: Additional information on Location Rakuten Crimson House (Head office) Additional information on English Qualification The applicants must have business level English skill. The interview will be conducted in English. #engineer #applicationsengineer #commerce #RakutenIchiba #Python #Csharp In Japanese, Rakuten stands for ‘optimism.’ It means we believe in the future. It’s an understanding that, with the right mind-set, we can make the future better by what we do today. So we challenge ourselves to evolve, innovate and experiment, to create a better, brighter future for everyone. Today, our 70+ businesses span e-commerce, digital content, communications and fintech, bringing the joy of discovery to almost 1.3 billion members across the world. If you have any trouble logging in, please contact us here Rakuten Group, Inc.: rakuten-recruiting-info@mail.rakuten.com Please read the Application Requirements(EN) / 募集要項(JP) before applying. Our Diversity & Inclusion Policy and Application Documents Rakuten’s corporate mission is to “contribute to society by creating value through innovation and entrepreneurship.” We foster a culture that provides equal opportunities to those who share this founding philosophy and take on the challenge to transform society, regardless of age, gender, nationality, or any other status. Diversity is one of Rakuten's core strategies and a driving force for innovation. Because of this, you are not required to submit any of the following information in order to apply for our job positions. - Gender - Age - Photo - Nationality - Information not related to business, such as ideological beliefs, family structure, etc. * For legal compliance, we may ask you about your work eligibility. See the details