Backend Engineer (Core Banking & Product Features)

**About the company:** PayPay Minato-ku, Tokyo With over 70M million registered users (as of July 2025), PayPay is the country’s most popular mobile wallet used by approximately one out of every two smartphone users in Japan. **Responsibilities:** Develop and operate backend applications in Java language (Java/Kotlin) for core banking systems Designing and developing for both performance and stability to maintain high reliability as a financial platform Understanding and implementing how to utilize infrastructure to solve system challenges Designing architecture based on application requirements and selecting middleware, etc. Performance tuning, monitoring settings, and alert response for microservices Requirements 3-5 years of backend development experience Practical experience in Java. Excellent skills in other common programming languages Understanding of data structures, algorithms, and the basics of object-oriented programming Schema design in DB (RDB, NoSQL, etc.) and efficient query creation Experience in web application development and tuning, and development with security considerations English (Business level conversational proficiency) Hands-on experience with AI/LLM tools (e.g., ChatGPT, GitHub Copilot, Gemini, CodeWhisperer, or similar) in professional software development. Nice to haves While not specifically required, tell us if you have any of the following. Development experience in the financial industry Experience implementing platform components such as RESTful API, Pub/Sub systems, database clients Development experience using AWS services Experience in system design, developing applications/web products handling large transactions, and applications/web products requiring scalability Experience with microservices Ability to conduct business in Japanese (native-level proficiency or equivalent to JLPT N1/N2) Proven track record of integrating AI-assisted development into system design and delivery Contributions to AI-related open-source projects or automation of workflows with AI is a plus APPLY FOR THIS POSITION DO YOU NEED MORE INFO? ASK A QUESTION About PayPay PayPay Minato-ku, Tokyo With over 70M million registered users (as of July 2025), PayPay is the country’s most popular mobile wallet used by approximately one out of every two smartphone users in Japan. Key benefits International engineering team Incredible scale Read more More jobs like this We'll send you a digest of new English-friendly software developer jobs in Japan. Your email stays private, we don't share or sell it. Apply for this position × I have a favour to ask. When you apply to PayPay, please select "Tokyo Dev" from the Application route field . This helps to keep this job board sustainable, so I'd be grateful for your support with this. - Paul, Founder of TokyoDev Continue applying © 2026 Privacy Policy **Requirements:** 3-5 years of backend development experience Practical experience in Java. Excellent skills in other common programming languages Understanding of data structures, algorithms, and the basics of object-oriented programming Schema design in DB (RDB, NoSQL, etc.) and efficient query creation Experience in web application development and tuning, and development with security considerations English (Business level conversational proficiency) Hands-on experience with AI/LLM tools (e.g., ChatGPT, GitHub Copilot, Gemini, CodeWhisperer, or similar) in professional software development. **Nice to have:** While not specifically required, tell us if you have any of the following. Development experience in the financial industry Experience implementing platform components such as RESTful API, Pub/Sub systems, database clients Development experience using AWS services Experience in system design, developing applications/web products handling large transactions, and applications/web products requiring scalability Experience with microservices Ability to conduct business in Japanese (native-level proficiency or equivalent to JLPT N1/N2) Proven track record of integrating AI-assisted development into system design and delivery Contributions to AI-related open-source projects or automation of workflows with AI is a plus APPLY FOR THIS POSITION DO YOU NEED MORE INFO? ASK A QUESTION About PayPay PayPay Minato-ku, Tokyo With over 70M million registered users (as of July 2025), PayPay is the country’s most popular mobile wallet used by approximately one out of every two smartphone users in Japan. Key benefits International engineering team Incredible scale Read more More jobs like this We'll send you a digest of new English-friendly software developer jobs in Japan. Your email stays private, we don't share or sell it. Apply for this position × I have a favour to ask. When you apply to PayPay, please select "Tokyo Dev" from the Application route field . This helps to keep this job board sustainable, so I'd be grateful for your support with this. - Paul, Founder of TokyoDev Continue applying © 2026 Privacy Policy