Senior Frontend Engineer

About HENNGE

HENNGE is a B2B SaaS company based in Tokyo Japan, and we are at the forefront of the changing workplace. HENNGE One, one of the top cloud security services in Japan, allows customers to adopt flexible work environments and safely harness the power of the cloud from any location. With cloud security ensured, employees are free to focus on working smarter, improving quality, and achieving business results. For further details regarding the engineering teams, products, and more, please visit this link.

Position

We are looking for a Senior Frontend Engineer to lead the frontend development of Tadrill, a specialized platform designed to build organizational resilience by equipping employees to identify and neutralize cyberthreats, especially phishing attacks. As a core component of HENNGE One Cybersecurity Edition serving over 2.8 million users globally, Tadrill transforms employee behavior through continuous, practical attack simulations, automated e-learning, and seamless reporting flows via Gmail and Outlook extensions. In this role, you will architect a high scale and self managed framework, turning complex security data into actionable insights through intuitive dashboards while serving as both a technical owner and a catalyst for team engagement.

While this role primarily focuses on the Cybersecurity Edition, we value engineers who are flexible and open to new challenges, with opportunities to move between teams and products through two-way discussions that support your growth and the company’s goals.

Tech Stack

Svelte w/ SvelteKit, Typescript, Playwright, Chromatic, Sentry, Go, AWS

What you’ll do

• Design, build, and ship new frontend features for the Tadrill platform, ensuring a high-quality user experience.
• Monitor, test, and improve the existing codebase to maintain speed and stability as the product scales.
• Collaborate closely with Backend Engineers, Designers, and Product Managers to turn requirements into practical, high-quality code.
• Identify areas for optimization across the entire application lifecycle to improve development efficiency and end-to-end performance.
• Participate actively in code reviews, technical discussions, and documentation to ensure long-term maintainability.
• Mentor junior engineers and contribute to a communicative, connected, and curious team environment.

Your qualification

• 3+ years of professional experience in frontend development with a strong focus on modern frontend frameworks (Svelte, React, Vue, Solid, Angular etc.)
• Either have used Svelte professionally, in personal projects or have strong interest in working with it.
• Proven track record of maintaining and scaling B2B SaaS products where stability and user-trust are paramount.
• Experience leading technical initiatives or mentoring engineers in a collaborative, cross-functional environment.
• High learning agility: the ability to dive into a specialized domain (Cybersecurity) and master a new stack with speed and curiosity.
• A proactive "owner" mindset: you drive the success of a feature from conception to deployment.
• Fluency in English (Japanese is not required), equivalent to CEFR B2 level or above (e.g., TOEIC 785+); an interest in working within a multicultural environment is essential.
• Interest in contributing to open-source projects or participating in the tech community.

Will be a plus

• Degree in Computer Science or related technical field.
• Experience with Go or other backend languages.
• Hands-on experience with cloud infrastructure (AWS, GCP, or Azure) and distributed system concepts.
• Knowledge in Cybersecurity (email security/phishing simulations), especially in the security awareness training domain.
• Experience with Google Workspace or Microsoft 365 integrations, particularly in developing Gmail add-ons and Outlook add-ins.
• Experience in technical project leadership (Team Lead equivalent) or people management (Engineering Manager equivalent).

Reasons why you will enjoy working at HENNGE

• We Celebrate Diversity

• Smooth Japan Relocation

• Balanced Work Life

• Passion for Technology

• Collaborative Teams

Work in autonomous teams where your decisions shape our services. Influence every aspect of our products, from UX and architecture to development and deployment, in an agile and collaborative setting.

Work Style

Flexible working hours with a designated core time (11:00–16:00), allowing you to organize your day effectively. Employees typically work 8 hours per day with a 1-hour break.

Employment Type

Permanent employee.

Place of Work

Tokyo, Japan — Shibuya Headquarters.

Compensation

Annual salary: 8.5 to 12.5 million JPY

(includes English Allowance and Physical Communication Bonus)

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:

Be part of a diverse and innovative team at HENNGE, where your passion for technology and desire to make a difference are valued and celebrated. Ready to change and challenge the status quo with us?

To learn more about life at HENNGE, please check these two links:

Selection Process

• Solve our online coding challenge. You will receive an email with our guidance upon your submission, and there is no time limit to finish the challenge. Please note that your application will be automatically rejected if you complete the coding challenge using a programming framework other than Svelte
• Upload your CV and Cover Letter.

• Casual interview with our HR
• 2 (or 3) interviews with our engineers (no live coding)
• Interview with our CEO

We value your time and want you to perform at your best, so the coding challenge will be the only technical assessment in the process. There will be no live coding sessions.

Have more questions? Please consult our FAQ.