Senior Backend Engineer (Principal/Tech Lead)

About PayPay

PayPay, a FinTech company that has achieved more than 69M users (as of May 2025) since its launch in 2018, is rapidly expanding its business scale as a payment platform used by approximately one out of every two smartphone users in Japan.

The company has a diverse team of professionals from more than 50 countries and is building a world-class engineering organization.

Our biggest competitor is "cash". They are seeking people who can accept this challenge positively, brush up on the product at a tremendous speed that other companies could never achieve, and who are passionate about promoting and spreading such a financial life platform in a short time along with professionalism.

PayPay is committed to maintaining a "Day 1" mindset, bringing to life visions of the future that no one else can even imagine. At PayPay, we provide an environment where everyone can deliver outstanding performance as professionals, through a flexible work style that includes remote and office.

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Position

PayPay is seeking a skilled Senior Backend Engineer (Principal/Tech Lead) to enhance our payment system, ensuring an optimal payment experience for our customers.

We are hiring for a range of senior positions & levels.  Offered position will be determined by demonstrated qualification and abilities.

Responsibilities: 

• Design and develop large-scale systems to support high throughput applications with complex requirements
• Utilize infrastructure effectively to address scalability challenges
• Contribute to open source projects and develop tools to improve system efficiency
• Embrace problem-solving as a core practice, focusing on root cause analysis and providing ongoing support for production code

Tech Stack:

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/AuroraDB, DynamoDB, ELK, Kafka, Redis, TiDB
• Deployment and Orchestration: Docker, Kubernetes, ArgoCD, AWS, GCP
• Development Tools: GitHub, IntelliJ, Gradle, Maven, npm/yarn, Flyway, Jenkins
• Data Analytics: BigQuery, Kibana, Spark
• Diagramming Tools: PlantUML, draw.io, miro.com
• Communication: Slack, Zoom

Portrait: 

• Experience: Demonstrated experience designing and implementing large scale, high performance, micro-service based architectures utilizing new concepts and technologies where appropriate 
• Ownership: A mentoring approach to owning, managing and improving the technical aspects of a large scale system end to end
• Communication: The ability to clearly and logically communicate your choice of technology and architectural decision based on its implementation strengths and limitations
• Commitment: As a professional, commit to the growth and business goals of the organization and create impactful results by your ownership
• Curiosity: Foster a development culture that explores new ideas knowing that we learn even from the ones that fail

Your qualification

• Proficiency in Java or equivalent programming languages (Scala, Python, Go)
• Eagerness to learn new languages and technologies as required
• Experience with SQL and NoSQL databases, as well as distributed caching
• Strong understanding of data structures, algorithms, and object-oriented programming principles
• Knowledge of concurrency and distributed computing
• Hands-on experience with RESTful APIs, Pub/Sub Systems, and Database Clients
• Familiarity with microservices architecture
• Previous involvement in designing and maintaining high-traffic systems
• Bachelor's degree in Computer Engineering, Computer Science, or equivalent experience in SaaS platform development (minimum 5 years)
• Fluent in English or Japanese

Preferred Qualifications:

• Previous experience in developing new products from inception
• Ability to design systems compliant with legal and security standards, with strong leadership skills for requirement identification
• Experience in improving system resilience and implementing disaster recovery strategies
• Awareness of market trends and needs, prioritizing speed and quality through MVP approaches
• Track record of delivering products within tight deadlines
• Commitment to continuous product improvement post-launch
• Strong cost-efficiency mindset with effective system cost analysis skills
• Willingness to share experiences and foster a culture of learning and improvement
• Experience in finance, payment, or related industries
• Additional language proficiency in Japanese and English is a plus
• Experience with AWS services

What we offer

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

Additional details

PayPay 5 senses

• Please refer PayPay 5 senses to learn what we value at work.

Employment Status

• Full Time

Office Location

• WFA(Work From Anywhere at Anytime)
• Remote Job
• You can live anywhere in Japan

Work Hours

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

Holidays

• 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.

Salary

• 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)