Senior TypeScript JavaScript Engineer

Senior TypeScript / JavaScript Engineer (5–7 Years Experience) Note: Must be currently in Japan & authorized to work Bilingual: Japanese (N2+) & Business English Role Details: We are looking for a highly skilled Senior TypeScript / JavaScript Engineer with strong backend expertise who can design and deliver scalable systems end‑to‑end. This role requires a proactive individual who takes full ownership of delivery, collaborates closely with product stakeholders, and supports team growth through mentorship. Key Responsibilities: Design, develop, and maintain robust, scalable backend systems using TypeScript/JavaScript Architect reliable systems from scratch, ensuring performance, security, and maintainability Collaborate directly with Product Owners (PO) to understand requirements and translate them into technical solutions Take end-to-end ownership of features and deliverables (on-time, high-quality) Contribute to frontend development (React / Next.js) when needed Drive best practices in code quality, system design, and deployment Mentor and support junior engineers, providing technical guidance and feedback Actively identify risks, propose improvements, and drive continuous optimization Required Qualifications: 5–7 years of professional experience in TypeScript / JavaScript development Strong expertise in backend development (Node.js or similar ecosystems) Ability to design and implement systems independently Proven track record of ownership and proactive delivery (with concrete examples) Experience working across both backend and, when needed, frontend technologies (React / Next.js) Strong communication skills with ability to handle technical discussions in Japanese (fluent level) Experience mentoring or supporting junior team members Strong sense of ownership and accountability Proactive problem solver with a can-do attitude Ability to balance technical excellence with delivery timelines Team player who enjoys collaborating and mentoring others Nice-to-Have Qualifications: Experience leading teams of 3 or more engineers Hands-on experience with AWS or other cloud platforms Experience working in Agile/Scrum environments Knowledge or experience with Java / Spring Boot Exposure to modern tech stacks, including microservices, serverless, or cloud-native architectures Experience leveraging or integrating AI/ML technologies in applications