Haken Senior Full Stack Engineer - React - Next.js
About the job
Join Japan's leading e-commerce technology group as a Senior Full Stack Engineer (Haken), building high-traffic subscription and membership platforms that shape the future of digital retail. This role offers the chance to work on mission-critical systems serving millions of users, using modern frameworks such as React, Next.js, and Node.js in a world-class engineering environment.
Key Responsibilities
- Lead end-to-end development of scalable web applications using React, Next.js, and Node.js
- Design robust architectures and conduct rigorous code reviews to maintain engineering excellence
- Drive performance optimisation initiatives focusing on Core Web Vitals, Lighthouse scoring, and caching strategies
- Collaborate with cross-functional teams to implement SSR, SSG, and ISR for superior user experience
- Maintain and enhance CI/CD pipelines and production environments to ensure 24/7 system reliability
Required Skills and Qualifications
Experience:
- 5+ years of professional experience in web application development or equivalent proven achievements
- Deep expertise in React, Next.js, and Node.js from initial design through production operations
- Strong proficiency in TypeScript within large-scale, production-level codebases
- Proven track record of performance optimisation (CDN/HTTP caching, rendering strategies)
Soft Skills:
- Strong collaboration and communication skills in cross-functional engineering teams
- Problem-solving mindset with attention to scalability and performance
- Ability to work independently in fast-paced, high-impact environments
Language Requirements:
- English: Business-level communication preferred
- Japanese: Not mandatory, but beneficial for local collaboration
- Valid residency in Japan with an appropriate working visa is required
Preferred Skills & Qualifications
- Experience developing subscription or SaaS platforms with complex membership structures
- Exposure to automated testing frameworks and CI/CD in microservices environments
- Familiarity with cloud-native tools (AWS/GCP) and container technologies such as Docker
About the Company
Our client is a global technology conglomerate behind Japan's largest digital ecosystem, spanning e-commerce, fintech, and telecommunications. Serving over 100 million members, the organisation is known for innovation, scale, and a highly international engineering culture. You will join a specialised unit developing a mission-critical subscription application managing complex billing and membership logic.
Why You'll Love Working Here
- Competitive hourly compensation with long-term contract stability
- International, English-centric tech hub located in central Tokyo
- Opportunity to work at unmatched scale impacting over 100 million users
- Modern engineering stack where performance metrics like Core Web Vitals and SSR/ISR are daily priorities
- Strong career development potential within one of Japan's most influential digital platforms
Don't Miss Out - Apply Now!
