Job Title:
Principal Backend Engineer (Kotlin)

Location:
Hybrid

Employment Type:
Full-time (Regular Employment)

Salary:
7,008,000 ~ 15,000,000 JPY

Open for applicants who is currently residing in Japan with valid working visa for non-Japanese citizen

About the Company

Founded in 2012 and headquartered in Minato City, Tokyo, this company is a rapidly growing enterprise listed on the Prime Market, employing approximately 2,800 people.

The company provides SaaS-based business support platforms for individuals, corporations, and financial institutions.

Business Areas:

• For individuals: personal finance and asset management applications, and economic media content
• For corporations and sole proprietors: cloud-based systems for accounting, invoicing, payroll, attendance, and expense management
• For financial institutions: Fintech platforms utilizing API integration

The company supports digital transformation for small businesses and sole proprietors by enabling automation and operational efficiency. It holds a strong market position in the cloud accounting sector and also offers services such as factoring and B2B invoice processing.

Global Expansion

The company is actively expanding globally, with development centers in Vietnam and India. English is the official language used within development teams, creating an environment where multinational engineers can thrive.

Diversity & Culture

Approximately 30% of engineers are non-Japanese, representing over 20 nationalities. The company promotes diversity, open communication, and a respectful, flat organizational culture.

The business continues to grow rapidly, supported by a strong engineering organization of nearly 500 professionals.

Your Role

As a
Principal Backend Engineer
, you will play a core role in building and evolving a cloud-based consolidated accounting platform. You will contribute both technically and culturally, helping strengthen backend architecture while mentoring engineers and promoting best practices across teams.

Key Responsibilities

• Promote knowledge sharing to improve overall team quality and autonomy
• Mentor team members to support technical growth
• Lead the design and implementation of complex backend features
• Architect high-speed, high-quality solutions based on business requirements
• Drive technical improvements to enhance development efficiency and shorten time to market
• Introduce and manage best practices and development tools
• Build a productive, challenge-driven development environment
• Foster a culture of innovation, collaboration, and continuous improvement

About the Product

The flagship product is a
cloud-based consolidated accounting platform
designed for group-level business management. It supports companies aiming for scalable growth beyond single-entity accounting and is increasingly adopted by businesses preparing for IPOs.

The platform delivers efficient and high-quality accounting operations, enabling streamlined inter-company coordination, data collection, and enhanced reporting through a flexible cloud architecture and intuitive UI/UX.

Technology Stack

Backend

• Kotlin

Frontend

• TypeScript, React,

Database

• MySQL (Aurora)

Infrastructure / Middleware

• AWS (ALB, EC2, RDS, S3, SQS, ElastiCache, EKS, etc.)
• SendGrid, GCP (BigQuery), Docker, Redis, Kafka, Maxwell, Elasticsearch, Fluentd, Envoy

Development Tools & Services

• Version Control: GitHub
• CI/CD: CircleCI, ArgoCD, GitHub Actions
• Environment Setup: Vagrant, Docker, Terraform Enterprise
• Monitoring: DataDog, Rollbar
• Communication: Slack, Zoom, Discord
• Ticket Management: Jira
• Security & Automation: OWASP ZAP, Burp Suite, VAddy, Dockle, Trivy

Requirements

Must-Have

• Experience developing and operating web applications using Kotlin or Java
• Ability to design scalable, maintainable code that delivers customer value quickly
• Deep technical expertise to establish and promote coding standards and best practices
• Experience mentoring and coaching engineers on effective code design
• Experience developing RESTful and GraphQL APIs
• Proficiency with relational databases (RDB)
• Experience with collaborative development using GitHub, CI systems, and lint tools

Nice-to-Have

• Experience with Agile/Scrum development across multiple teams
• Experience as an AI software engineer
• Hands-on experience as a Software Engineer in Test (SET)
• Practical knowledge of Site Reliability Engineering (SRE)
• Infrastructure experience with Docker, AWS, Kubernetes, and Terraform
• Experience in performance tuning for large-scale data systems

Ideal Candidate

• Proactive and team-oriented, with a continuous improvement mindset
• Strong communicator who fosters collaboration
• Willing to propose ideas and take initiative
• Interested in both technology and business impact
• Curious, motivated, and focused on delivering real user value

Work Environment & Benefits

• Choice of MacBook Pro, MacBook Air, iMac, or Windows PC
• Regular device upgrades and custom configurations available
• All necessary equipment provided by the company
• Internal library system for technical and management books
• Referral incentives and recruitment meal coverage
• Conference participation support (e.g., RubyKaigi, Google I/O)

Working Conditions

• Working Hours: 9:30 – 18:30
• Break Time: 60 minutes
• Flextime: Yes
• Holidays:
• Saturdays & Sundays
• National Holidays
• Summer Holiday
• End-of-Year & New Year Holiday
• Other special holidays

Insurance

• Workers' Accident Compensation Insurance
• Unemployment Insurance
• Welfare Pension Insurance
• Health Insurance

We have
more positions available
—if you're open to new opportunities,
don't hesitate to apply

Job ID: 06962