Backend Engineer

About the role

About PayPay

PayPay is a FinTech company that has grown to over 75M (as of August 2026) 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. PayPay 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 PayPay with professionalism and passion. ※ Please note that you cannot apply or be selected in parallel with PayPay Corporation, PayPay Card Corporation and PayPay Securities Corporation.

Job Description

PayPay is looking for a Backend Engineer to work on our payment system to deliver the best payment experience for our customers.

AI-First Culture at PayPay

At PayPay, we believe that the future of software development is AI-augmented. Every engineer is expected to actively leverage AI tools for code reviews, testing, documentation, debugging, and productivity. AI is not optional — it is a mandatory part of our daily engineering workflow. Candidates must demonstrate both experience and mindset in utilizing AI effectively to deliver high-quality systems faster and better.

Main Responsibilities

- Design large-scale systems with high complexity to support our high throughput applications.

- Understand how to leverage infrastructure for solving such large-scale problems.

- Develop tools and contribute to open source wherever possible.

- Adopt problem solving as a way of life – always go to root cause! Support the code you write in production.

- Leverage AI/LLM-based tools for code development, reviews, testing, and documentation in daily workflows.

Tech Stack

We select the best combination of tech at times. | Java, Kotlin, Scala | Spring Boot, JUnit, Resilience4j, Feign | MySQL/AuoraDB, DynamoDB, ELK, Kafka, Redis, TiDB | Docker, Kubernetes, ArgoCD, AWS, GCP | GitHub, IntelliJ, Gradle, Maven, npm/yarn, Flyway, Jenkins, snyk, | Bigquery, Kibana, Spark | PlantUML, draw.io, miro.com | Slack, Zoom

Qualifications

- 4+ years of experience in using Java under professional environment, or if you are non-Java user, excellent skills in generalized programming languages, such as Scala, Python, and Go.

- Interest and ability to learn other coding languages as needed.

- Experience with NoSQL databases and distributed cache.

- Strong fundamentals in data structures, algorithms and object-oriented programming.

- In-depth understanding of concurrency and distributed computing.