Principal Software Engineer

Pay Pay is a Fin Tech company that has grown to over 70M (as of July 2025) users since its launch in 2018. Our team is hugely diverse with members from over 50 different countries.

OUR VISION IS UNLIMITED_

We dare to believe that we do not need a clear vision to create a future beyond our imagination. Pay Pay will always stay true to our roots and realize a vision (future) that no one else can imagine by constantly taking risks and challenging ourselves. With this mindset, you will be presented with new and exciting opportunities on a daily basis and have the opportunity to grow and reach new dimensions that you could never have imagined.

We are looking for people who can embrace this challenge, refresh the product at breakneck speed and promote Pay Pay with professionalism and passion.

※ Please note that you cannot apply or be selected in parallel with Pay Pay Corporation, Pay Pay Card Corporation and Pay Pay Securities Corporation.

• Drive teams to expand and optimize technical vision, architecture, system design, development process of systems
• Work with teams to answer consultations; furthermore, identify and prioritize tech debt and determine the best approach for resolving it.
• Realize the vision through measurable gains in system scalability and efficiency.
• Serve as a role model for junior engineers through mentoring and direct education.

We are looking for a Principal Software Engineer to work on our various systems which need high scalability, reliability and availability. These challenges require creative thinking and a deep understanding of how software and platform work.

Our ideal candidate is an ace problem solver and a learner  should have a very high degree of comfort in a programming language of your choice. We offer a flexible work schedule and you get your choice of tools (both hardware and software) and most importantly, the opportunity to work on tough problems with the brightest minds around you. So, if challenges excite you, and you're ready for a big one, let us know.

Responsibilities:

• Design, develop, test, deploy, maintain and improve software and core platform
• Lead technical aspects for multiple projects through hands‑on execution and guidance of other engineers
• Provide architectural blueprints and technical leadership.
• Provides input and guidance during all phases of programs to solve challenging technical issues.
• Build common platforms to support different business vertical application systems
• Develop tools and contribute to open source wherever possible
• Adopt problem‑solving as a way of life – always go to the root cause!

Experience:

• Solid foundation in designing, implementing, and maintaining a large‑scale distributed system.
• Experience in developing distributed platform systems such as Messaging Platforms, Pub/Sub Systems, Databases, Distributed Computing Frameworks, and Schedulers.

Our technology stack may vary based on project needs. Currently, we utilize:

• Programming
  
  Languages:
  
  Java, Kotlin, Scala
• Frameworks and Tools:
  Spring Boot, JUnit, Resilience4j, Feign
• Databases:
  MySQL/Aurora
  
  DB, Dynamo
  
  DB, ELK, Kafka, Redis, TiDB
• Deployment and Orchestration:
  Docker, Kubernetes, ArgoCD, AWS, GCP
• Development Tools:
  Git Hub, Intelli
  
  J, Gradle, Maven, npm/yarn, Flyway, Jenkins
• Degree in Computer Engineering or Computer Science or 7+ years equivalent experience in software development
• Strong fundamentals in data structure, algorithm, operating system and object‑oriented programming
• Deep understanding of concurrency, distributed computing, large‑scale system, messaging and algorithm
• Software development experience in one or more general‑purpose programming languages
• Interest and ability to learn new technology stacks as needed

Preferred Qualifications:

• Experience in working for system development in finance, payment, or similar industries
• Experience with AWS services
• Contribute to open‑source projects
• Language ability in Japanese and English is a plus (We have a professional translator but it is nice to have language skills)
• Experience: Demonstrated experience designing and implementing large scale, high performance, micro‑service based architectures utilizing new concepts and technologies…