We’re looking for a senior front-end engineer who thrives in a growth-oriented environment. You will join the Access Control Team, responsible for the HENNGE One Identity Edition, which is part of the HENNGE One suite used by over 2.8 million users across various companies. You will develop and refine core features using TypeScript in React to create seamless user experiences for enterprise clients. We value engineers who are flexible and open to challenges, with opportunities to move between teams through two-way discussions that align with both personal growth and company goals.
Tech Stack: TypeScript with React, React Router, TailwindCSS (with Class Variance Authority),TanStack Query, TanStack Store, Playwright
Responsibilities
- Build and improve core front-end features of HENNGE One Identity Edition using TypeScript in React, implementing high-fidelity UI that delivers secure and seamless experiences for enterprise users.
- Take ownership of the full development cycle, from implementation to CI/CD pipelines, testing, and documentation, while continuously improving performance, scalability, and maintainability through modern front-end best practices.
- Collaborate with Design, Product Management, and Customer Success teams to translate ideas and customer feedback into intuitive and polished interfaces.
- Participate in technical discussions and contribute to architectural and product decisions that shape the future of HENNGE One.
- Support teammates through code reviews, knowledge sharing, and open collaboration to foster a culture of continuous learning.
Requirements
- 3+ years of professional experience building production-grade web applications using React and TypeScript, with the ability to write type-safe, maintainable code and work with modern React frameworks (e.g., Next.js, Remix, React Router).
- Experience working cross-functionally with PM, UI/UX, QA, and backend teams, and delivering features end-to-end with ownership, including mentoring junior engineers as needed.
- Strong understanding of core frontend application architecture, including complex state management (Redux, Jotai, TanStack Store, etc.), implementing authentication & authorization flows, and integrating APIs using type-safe patterns.
- Ability to write robust tests (unit, integration, E2E) and experience working with CI/CD pipelines.
- Familiarity with performance optimization, secure coding practices, working effectively in very large codebases, accessibility fundamentals, and maintaining good documentation.
- Interest in contributing to open-source projects or participating in the tech community.
- Fluency in English (Japanese is not required), equivalent to CEFR B2 level or above (e.g., TOEIC 785+).
Nice to haves
While not specifically required, tell us if you have any of the following.
- Degree in Computer Science or other related technical fields.
- Familiarity working with UI/UX designers and interpreting design specifications (e.g., Figma).
- Experience with observability and analytics tooling (e.g., Sentry, Datadog, New Relic, PostHog, Amplitude).
- Awareness of accessibility and compliance standards (WCAG, security best practices).
- Working knowledge of Unix-like environments and cloud-native development (Docker, Kubernetes, or AWS/Azure/GCP).
- Proficiency with modern React patterns (function components, hooks, server components, and related tooling).
- Team leadership experience.
Compensation
¥8,500,000 ~ ¥12,500,000 annually.
Our salary range is inclusive of English Allowance & Physical Communication Bonus - please check the details below, with the final amount determined based on your experience and skills.
Please refer to our Company Introduction Deck for an explanation of our Assessment System and the Belt System, which we use to determine the candidate’s salary range.
Benefits
- English Allowance and Advanced Language Expert Allowance: JPY 10,000 ~ JPY 130,000 per month, paid alongside base salary, if the employee fulfills the requirements.
- Physical Communication Bonus: JPY 4,000 per day, applicable from October 2025 onwards, for coming to the office and interacting with other employees, paid out as bonus according to the number of days.
Details will be provided at the offer meeting.
