Senior Software Engineer (Backend/Infrastructure) - HENNGE Secure Transfer

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About HENNGE Join us at HENNGE, a Tokyo-based cloud-security company with the No. 1 IDaaS revenue share*, helping organizations adopt flexible work environments and safely leverage the cloud. As a B2B SaaS company, we build secure and reliable cloud solutions that help customers manage access and identity efficiently. Our flagship product, HENNGE One, empowers customers with access control, email filtering, archiving, and next-gen cloud security features. What makes us unique: a highly technical CEO, strong engineering culture, and a global mindset. For further details regarding the engineering teams, products, and more, please visit this link: company introduction deck. *No. 1 IDaaS vendor by revenue share, FY2021–FY2025 (forecast), per ITR Market View 2026.

Role overview We are looking for a Senior Software Engineer to take ownership of backend and web-platform development for HENNGE One, our flagship cloud-security suite used by organizations across a wide range of industries. As a B2B SaaS leader in Japan, we provide mission-critical security solutions that empower customers to work safely from anywhere. In this role, you will join the Secure Transfer Team, responsible for the development of HENNGE One Data Loss Prevention (DLP) Edition. You will be developing our high-security file exchange solution, which serves as a core component of our product ecosystem. Your mission is to architect scalable and fault-tolerant systems in a distributed cloud deployment to handle and protect sensitive enterprise data. This position requires you to maintain and improve our system architecture leveraging a deep knowledge of AWS and Kubernetes (alongside tools like Terraform), combined with a strong passion for backend application development. While this role primarily focuses on the DLP 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: FastAPI, Kubernetes, ArgoCD, PostgreSQL, AWS

What you’ll do

• Design, build, and maintain new features for HENNGE One, using Python and other web technologies.
• Architect scalable, fault-tolerant services deployed in cloud environments
• Automate deployment, testing, monitoring and documentation via CI/CD pipelines and infrastructure-as-code.
• Collaborate closely with Product Management, Design, and Customer Success teams to deliver high-quality user experiences.
• Participate actively in code reviews, discussions and technical decision-making.
• Mentor junior engineers, and contribute to improving team processes and engineering culture.

What we’re looking for Minimum Qualifications:

• 3+ years of experience developing production-scale web applications using Python.
• Strong experience across the software development lifecycle (SDLC), from system design to deployment and maintenance.
• Hands-on experience with containerization and orchestration technologies (e.g., Kubernetes, ArgoCD).
• Experience with Infrastructure-as-Code tools, such as Terraform.
• Deep expertise in architecting and operating mission-critical AWS environments
• Experience with CI/CD pipelines, automated testing, and clean-code practices.
• Ability to lead technical initiatives, mentor junior engineers, and work collaboratively in a team environment.
• Fluency in English (Japanese is not required), equivalent to CEFR B2 level or above (e.g., TOEIC 785+).
• Interest in open source or tech community activities.

While not required, we’d love to hear if you have:

• Degree in Computer Science or related technical field.
• Experience building large-scale distributed systems or SaaS products.
• Familiarity of Go, or a strong interest in learning it, to help build and maintain our multi-language backend infrastructure.
• Additional experience with cloud security best practices, including PII obfuscation and secure data-handling protocols.
• Team leadership experience.

Work Style & Employment Details 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. (Relocating to Shinjuku starting April 2027)

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.

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 5,000 per day 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.
• Transportation allowance (maximum of JPY 35,000 per month).
• Employee Stock Ownership Plan.
• Insurance: Health, Employment, Industrial Injury, Welfare pension.
• Opportunities to attend international and domestic conferences.
• Financial support for technical certifications and technical learning programs.

【Reasons why you will enjoy working at HENNGE】 🌎 We Celebrate Diversity Join a vibrant team from over 20 countries, united by a love for technology and Japanese culture. Located in Shibuya, Tokyo, we offer a dynamic, non-traditional work environment in one of the world's most exciting cities.

📍 Smooth Japan Relocation We make your move to Japan smooth and stress-free. We provide comprehensive support such as flight tickets, visa sponsorship, and Japanese lessons, to ensure a smooth onboarding process for our new hires, ensuring a seamless transition and a warm welcome for all candidates.

🎉 Balanced Work Life Work-life balance is highly valued at HENNGE, and lots of fun happens at our office! 200+ of social channels in our Slack, from weekly board game nights to snowboarding club, internal and seasonal events, monthly tech sessions with beer bashes, attendance of international tech conferences, and more. Employees have access to a flexible working hours system (with core working hours) to accommodate their preferred working style.

❤ Passion for Technology Our CEO has an engineering background and remains deeply engaged in product development. This hands-on understanding of technology helps shape a culture where thoughtful design, technical quality, and continuous improvement are genuinely valued. For engineers, this means working in an environment led by someone who understands the challenges of building products and actively supports teams in doing their best work.

🙌 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.

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: Life at HENNGE Stories from our employees

Hiring process If you are also interested in the Senior Software Engineer, (Python/Web Dev) – HENNGE Access Control position, you do not need to submit applications for both roles. Since both positions share the same hiring pipeline, one application is sufficient. Please simply indicate your interest in both roles in your cover letter.

• 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 have fewer than three years of professional Python experience, and/or
• you complete the coding challenge using a programming language other than Python.
• Upload your CV and Cover Letter. Please check our guide on how to prepare them here.
• 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.