Backend Engineer

Applications: candidates must already be in Japan. Visa sponsorship: not available. Japanese: Business level. English: Business level. Japan Dev tags: Engineering, Backend, Go, Ruby, React, Typescript.

Job Description

About the Role

We operate one of Japan's largest influencer platforms, with a community of approximately 90,000 registered influencers.

In February 2026, we officially launched Vooster, a new AI-powered influencer marketing platform that automatically matches brands with the most suitable influencers and uses AI-powered engagement prediction to enable performance-based pricing.

Vooster is positioned as the company's next major growth driver, and we're making significant investments to rapidly scale both the product and the business.

Our engineering organization consists of around 30 engineers, and we've moved quickly by working closely with talented external partners. As Vooster enters its next stage of growth, we're bringing more core engineering expertise in-house and looking for experienced technical leaders who can shape key architectural decisions and help build the foundation of our next-generation platform.

What You'll Do

You'll take ownership of the backend architecture and technical direction of Vooster.

This is far more than an implementation role. You'll work closely with product and business teams to translate business strategy into scalable technical solutions, make critical architectural decisions, and help establish engineering practices that enable long-term growth.

Key Responsibilities

• Design, develop, and operate the backend systems powering Vooster
• Lead technical decision-making and define the overall system architecture
• Translate business goals and product roadmaps into scalable technical solutions
• Evaluate and select technologies while documenting key architectural decisions through ADRs (Architecture Decision Records)
• Drive technical discussions and build consensus across the engineering organization
• Mentor junior engineers through technical coaching and code reviews
• Improve engineering productivity by establishing development standards and strengthening code review culture
• Help reduce technical debt while building the foundation for our next-generation platform

Why You'll Love This Role

• Build a Product from the Ground Up

Join Vooster during its early growth stage and play a central role in shaping both the product and its technical foundation—from product strategy through architecture and implementation.

• Direct Impact on Business Growth

Every morning, our engineering team reviews product dashboards to see how yesterday's releases impacted business performance. Engineers don't wait for detailed specifications—they actively help decide what should be built next based on real-world data and customer needs.

• Focus on Technical Leadership

Our Engineering Managers handle people management, allowing you to focus on what you do best: solving difficult technical challenges, designing scalable systems, improving AI-powered matching, and building the architecture that supports the company's future growth.

Tech Stack

• Backend: Node.js, Ruby, Go
• Frontend: TypeScript, React
• Cloud & Infrastructure: AWS
• Development Tools: GitHub, DataDog, Linear

Required Qualifications

• 5+ years of experience developing web applications (using any programming language), or equivalent practical experience
• Experience leading engineering teams as a Tech Lead or Engineering Manager
• Experience making architectural decisions and designing large-scale systems
• Experience proactively selecting technologies and documenting architectural decisions (such as ADRs)
• Business-level Japanese proficiency is required

Nice to Haves

• Experience developing applications with TypeScript on AWS or Google Cloud Platform
• Experience designing highly scalable systems capable of handling significant traffic
• Experience introducing AI-assisted development workflows or improving engineering productivity
• Experience establishing testing strategies, coding standards, or engineering best practices across teams
• Native-level Japanese proficiency or JLPT N1 certification is preferred