Senior Front-end Engineer (React, Japan)

Roles

We’re currently looking for a Senior Front-end Engineer (React) to join our fast-paced growing team. As part of the engineering team, you will be responsible for building cloud-security solutions used by thousands of enterprise companies. Our flagship product, HENNGE One, provides functionalities ranging from access control, email filtering, online storage, and email archiving. We focus on implementing state-of-the-art security functionalities, ensuring SLA 99.9% in distributed fault-tolerant deployment, and providing the best user experience to our customers.

Responsibilities

• Design, develop, and maintain innovative features based on business needs
• Bring our design system to life by implementing high-fidelity UI using a modern frontend framework
• Ensure high-quality deliverables through CI/CD pipelines, tests, and documentation
• Collaborate with Design, Product Management and Customer Success teams to continuously improve the product
• Support the team by actively participating in discussions and reviewing others' code
• Improve team synergy and mentor junior engineers

Our Tech Stack

Each product team is free to choose their own tech stack. Each project uses Typescript as the base language, with a combination of these technologies:

React:

• Styled Components
• Redux (Toolkit)
• RxJS
• Jest/Testing Library
• Testcafe

For more information, you can also check our Stackshare page out.

Requirements

Minimum Qualifications

• 3+ years of web development experience, with at least 3+ years in React.
• Ability to write proper type-safe code with Typescript
• Ability to mentor junior engineers and work collaboratively in a team environment
• Ability to write robust tests along with your code
• Understand the importance of clean code and software documentation
• Business-level English (Japanese is NOT required)
• Interested in open source/tech community activities

Meet at least three of the following criteria:

• Degree in Computer Science or other related technical fields
• Experience with state management in a complex web app (e.g. Redux, Vuex)
• Familiarity with design collaboration tools like Figma
• Knowledge setting up build and test environments, CI/CD pipelines
• Knowledge of Unix-like environment
• Team leadership experience
• Experience with Function Components and Hooks

Benefits / Working Conditions

Employment Type Permanent Employee Place of Work Japan, Tokyo, Shibuya HQ Hybrid work environment with emphasis on in-office collaboration and encouragement for employees to work onsite. Working Hours 10:00 — 19:00 Flex Time (Core time is 11:00 — 16:00) with 1 hour break.

Remuneration

• We generally offer a salary range of JPY 8.5M to 12.5M (English Allowance & Physical Communication Bonus inclusive — 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: https://speakerdeck.com/hennge/company-introduction-deck-hennge

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* for coming to the office and interacting with other employees, paid out as bonus according to the number of days. (*Applicable from October 2025 onwards) Details will be provided at the offer meeting.
• Insurance: Health, Employment, Industrial Injury, Welfare pension
• Transportation allowance (maximum of JPY 35,000 per month)
• Employee Stock Ownership Plan
• Opportunities to attend international and domestic conferences
• Financial support for technical certifications and technical learning programs

Application Process

1. Solve our coding challenge from the link below: https://challenge.hennge.com/?entry-code=WORK-UA-REACT-SR You will receive an email with our guidance upon your submission, and there is no time limit to finish the challenge.
2. Once you finish the coding challenge, follow the instructions to upload your CV and Cover Letter.
3. Casual interview with our HR
4. 2 (or 3) interviews with our engineers
5. Interview with our CEO