Senior Frontend Engineer

On behalf of our Client from Japan, Mobilunity is looking for a Senior Frontend Engineer 

Our client is a fast-growing fintech company based in Tokyo that offers its real-time, monthly consolidated credit service all across Japan. Our client started Japan’s first instant post-pay credit service for e-commerce customers in October 2014. The main product is an online payment platform that requires no pre-registration or credit card to use; via this service, the customers can purchase products online using only a mobile phone number and email address and settle a single monthly bill for all their purchases, either at a convenience store, by bank transfer, or auto debit. Customers can use credit funds during a month and then return the balance to zero without paying credit interest.

This service also supports multi-pay installments and subscriptions. There are currently over 4 million accounts in use. This service got the largest investment to date in the Japanese financial tech industry, including a PayPal Ventures investment.

Key  Responsibilities:

• Build and maintain scalable, high-quality front-end applications using React.js
• Translate complex product requirements into clean, intuitive, and pixel-perfect UI
• Collaborate closely with Product, Design, Infrastructure, and Operations teams
• Develop reusable components and front-end architecture patterns for long-term scalability
• Optimize applications for performance, accessibility, and responsiveness
• Instrument applications with monitoring, logging, and alerting for reliability and observability
• Participate in code reviews and maintain high engineering standards across the team
• Work across multiple internal and external products, adapting to varied domain requirements
• Contribute to technical discussions, architecture decisions, and design improvements

Requirements:

• Strong experience with React.js, Typescript, React Native, Expo, Expo Web, Redux, and modern front-end ecosystems
• Proficiency with ES6+, Redux, Webpack, and related tooling
• Experience with Next.js, Redux Toolkit, Zustand, Three.js
• Experience working in large-scale, multi-stakeholder codebases
• Strong understanding of UI/UX principles and ability to build pixel-perfect interfaces
• Focus on performance, maintainability, and testability of code
• Experience collaborating in cross-functional agile teams
• Ability to connect multiple services and workflows even in unfamiliar domains
• Strong communication skills and proactive problem-solving mindset

Nice to have:

• Experience building B2C consumer-facing products
• Background in fintech, payments, or financial systems
• Experience with design systems or scalable UI frameworks
• Familiarity with observability tools (monitoring, logging, analytics)
• Experience mentoring engineers or leading front-end initiatives

In return we offer:

• The friendliest community of like-minded IT-people
• Open knowledge-sharing environment – exclusive access to a rich pool of colleagues willing to share their endless insights into the broadest variety of modern technologies
• Paid vacations and sick leaves, including 5 paid days per year that don’t require a sick note
• English classes in 1-to-1 & group modes with elements of gamification
• Neverending fun: sports events, tournaments, music band, multiple affinity groups

🐳 Come on board, and let’s grow together! 🐳