ミツモアのミッション

「日本のGDPを増やし 明日がもっといい日になる と思える社会に」

労働生産性が先進国の中で低く、GDPも実質賃金も下がり続けている日本。
その閉塞感を打破するために、ミツモアはサービス産業の生産性向上を追求します。
まずは集客や見積もりを自動化するプラットフォーム「ミツモア」で、そして事業者のオペレーションの全てを効率化するSaaS「プロワン」で、さらに「プロワン」のインフラ環境と「ミツモア」で活躍する豊富なプロネットワークを掛け合わせた受発注DXサービス「ハッチュー」で。
サービス・プロダクトの利用者は急激に増えていますが、それでも目指す所へはまだ一合目。
途方もなく高い山だからこそ同じ想いを持ち、ユーザーやプロダクトにまっすぐに向き合える仲間と一緒にのぼりたい。
私たちと一緒に、世界基準のサービスを通じて、明日はきっといい日になると信じられる世の中を実現していきましょう。

About the position

We’re looking for a Senior Software Engineer who is passionate about building reliable, scalable, and maintainable systems—from backend business logic to frontend user experiences.

You’ll work primarily with TypeScript, with React on the frontend and Nest.js/Prisma on the backend. You’ll collaborate closely with both engineers and non-engineers (product, design, biz/ops) to ship features that power the core of our product for some of Japan’s largest enterprise customers.

You’ll have the opportunity to:

• Design and deliver features end-to-end across the stack (frontend, backend, architecture)
• Take ownership of technically challenging projects, such as algorithm optimization, complex data modeling, or new platform integrations
• Shape and evolve our core backend and data persistence layers
• Drive improvements in system reliability, performance, and maintainability
• Mentor other engineers and champion high standards in code quality and architecture
• Contribute to key open source projects and upstream dependencies as part of your normal workflow

We value engineers who care deeply about technical quality, end-user experience, and long-term stability—not just shipping tickets fast.

Our Tech Stack

Not exhaustive, but the most important are:

• TypeScript everywhere.
• NodeJS.
• React.
• MongoDB.
• AWS (Specifically ECS, CloudFront, S3, SQS, Lambda)
• Vercel.
• Redis.

Requirements

• 7+ years of professional software engineering experience
• Significant experience with TypeScript
• 2+ years of hands-on work with React (or a similar modern frontend framework)
• Strong understanding of backend frameworks, database modeling (SQL/Prisma), and asynchronous app architecture
• Proficiency collaborating across functions (product, design, operations, and stakeholders)
• Track record of delivering production systems with an emphasis on reliability, testability, and maintainability
• Familiarity with modern development workflows: Git, PR reviews, CI/CD, and automated testing

Nice to haves

While not specifically required, tell us if you have any of the following.

• Development and operation using containers (e.g. Docker)
• Cloud infrastructure experience (e.g. AWS or GCP)
• Machine learning or recommendation engines
• Performance measurement and bottleneck investigation
• Conversational-level Japanese (equivalent to JLPT N3 or greater).