Senior Platform Engineer (Application Layer)

Leading HR SaaS Company | Full Remote (Japan) | JPY 9.5M - 15M

About the Role

This is platform engineering at the application layer, not infrastructure. You will build the shared features that every product in a growing HR and payroll suite relies on, so products connect seamlessly for customers ranging from small businesses to large enterprises. Infrastructure is owned by a separate SRE team.

What You Will Do

• Design, build, and run cross-product platforms: permissions, billing, tasks, event integration, and data APIs
• Lead architecture decisions from design through implementation and operation
• Evolve existing platforms and APIs safely, including migration planning
• Support product teams with design reviews and technical guidance

Requirements

• 5+ years of web application development using a framework (any language, e.g., Go, Python, TypeScript, Java)
• Experience developing an in-house product
• Data modeling and performance tuning on a commercial product
• Team leadership experience
• Business-level Japanese

Nice to Have

• Ruby on Rails, or openness to working in Ruby after joining
• Shared platform or common infrastructure design
• Large-scale re-architecture or phased migration experience
• GCP / AWS experience

Career Paths

• IC / Specialist track
• Playing Manager track, leading 3-5 engineers
• Growth path to Engineering Manager and Director

Work Style

Full remote within Japan. Small team, 1-week Scrum sprints.