About PayPay

PayPay is a fintech company that has grown to over 58M users since its launch in 2018. Our team is hugely diverse with members from almost 50 different countries. To build "PayPay", we allied with Paytm; the biggest payment service company in India. Based on their customer-first technology, we created and expanded the smartphone payment service in Japan. Our biggest competitor is "cash". We seek people who can accept this challenge positively, brush up the product at a tremendous speed, and promote PayPay with professionalism and passion.


Job Description


The PayPay Core Engineering team is looking for Java developers to work on improving our suite of internal libraries.

PayPay Core Engineering focuses on addressing core technical problems, leading the improvement of development practices at PayPay and supporting our development teams through a suite of internal libraries streamlining technical functions such as database queries, queue management, logging, monitoring, and encryption. A strong candidate for Core Engineering will have a background in Java/Kotlin product development, good understanding of interactions between the application and the infrastructure, and a strong knowledge of inner working of Java and database management systems.

Team Missions

  • Provide and own solutions used in multiple teams as standards and maximize the effectiveness
  • Make complex problems simple
  • Lead knowledge sharing and technical education

Primary Responsibilities

  • Maintaining and implementing new core libraries used by the product development teams - this imposes high requirements on the code quality, test coverage, well designed architecture and everything required to produce high quality libraries
  • Investigating complex performance issues
  • Active participation in improving Java/Kotlin development practices in PayPay - identifying root causes of inefficiencies and technical defects in product development, proposing potential solutions and driving them to the end

Supporting Responsibilities

  • Constant technical improvement and research of the new technologies and best practices
  • Assist product development teams in the adoption and updates of internal libraries
  • Assist development and infrastructure teams in investigating root causes of complex technical issues


  • 3+ years of product development in Java/Kotlin; 6+ years of total development experience
  • Experience working with Kafka, MySQL, ElasticSearch or similar technologies
  • Experience developing and maintaining high-load high-availability scalable systems
  • Experience in application and database performance optimization

Preferred Qualifications

  • Working knowledge of Gradle and developing Gradle plugins
  • Experience with TiDB
  • Experience implementing and maintaining technical libraries

PayPay 5 senses

Working Conditions 

Employment Status

  • Full Time

Office Location

Work Hours

  • Super Flex Time (No Core Time)
  • In principle, 10:00am-6:45pm (actual working hours: 7h45m + 1h break)


  • Every Sat/Sun/National holidays (In Japan)/New Year's break/Company-designated Special days

Paid leave

  • Annual leave (up to 14 days in the first year, granted proportionally according to the month of employment. Can be used from the date of hire)
  • Personal leave (5 days each year, granted proportionally according to the month of employment)
    *PayPay's own special paid leave system, which can be used to attend to illnesses, injuries, hospital visits, etc., of the employee, family members, pets, etc.


  • Annual salary paid in 12 installments (monthly)
  • Based on skills, experience, and abilities
  • Reviewed twice a year
  • Special Incentive once a year *Based on company performance and individual contribution and evaluation
  • Late overtime allowance, Work from anywhere allowance (JPY100,000)


  • Social Insurance (health insurance, employee pension, employment insurance and compensation insurance)
  • 401K
  • Language Learning support
  • Translation/Interpretation support
  • VISA sponsor + Relocation support

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