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! 🐳