Senior Full Stack Engineer (Ruby)

🚀 Senior Full-Stack Engineer (Ruby) | Tokyo | Hybrid | Relocation Support Available

I'm currently partnering with one of Japan's leading fintech and AI-driven SaaS companies to hire a Senior Full-Stack Engineer who wants to build products used by hundreds of thousands of businesses across Japan.

This is an opportunity to join a highly collaborative engineering organization that is entering its next growth phase, leveraging AI to transform enterprise software while continuing to scale one of Japan's most successful B2B SaaS platforms.

📍 Location: Tokyo (Hybrid – 2 days/week in the office)

You'll be based in the Tokyo office while working closely with a larger engineering team in Fukuoka, collaborating across offices with some of the company's top engineers.

💰 Salary: ¥7,008,000–¥11,004,000 performance bonus

What you'll be doing:

💻 Design and build large-scale web applications using Ruby on Rails and modern frontend technologies such as React, TypeScript, and Next.js.

🏗️ Solve complex technical challenges by designing scalable, maintainable architectures and translating business requirements into robust engineering solutions.

🤝 Provide technical leadership through code reviews, mentoring, architectural discussions, and engineering best practices.

Tech Stack:

• Ruby on Rails
• React / Next.js / TypeScript
• GraphQL
• AWS & GCP
• Docker, Terraform
• MySQL, Redis, Kafka
• GitHub Actions, CircleCI

We're looking for someone who has:

✅ 5 years of backend development experience (Ruby on Rails or similar frameworks)

✅ Experience building modern frontend applications with React, Vue, or similar SPA frameworks

✅ Strong software architecture and system design skills

✅ Experience leading technical initiatives and mentoring engineers

✅ Passion for building high-quality products that scale

✅ Ideally Conversational Japanese (N3 level)

Nice to have:

⭐ GraphQL

⭐ Domain-Driven Design / Clean Architecture

⭐ Agile (Scrum)

⭐ Experience with AI technologies or using AI tools in software development

Why consider this opportunity?:

✨ Join one of Japan's most respected engineering organizations.

✨ Work on products with real impact for businesses nationwide.

✨ Be part of the company's AI transformation journey and help shape next-generation enterprise software.

✨ Collaborate with experienced engineers across both the Tokyo and Fukuoka offices.

✨ Flexible hybrid working environment.

✨ English-friendly engineering culture

✨ Relocation support available.

If you're interested, please apply to this role !