東京

Senior Full-stack Engineer

Tokyo
Remote OK - Anywhere in Japan
Full-time
March 24, 2025

About KOMOJU

KOMOJU (by Degica) is the leading cross-border payment gateway for Japan. We power payments for companies like video game distribution platform Steam and the popular mobile app TikTok. Today we help thousands of merchants by providing them with the payment infrastructure they need through developer-friendly API’s to integrations on popular platforms like Shopify and Wix; we help our merchants grow in all markets they are expanding.

What to expect

We are product focused, meaning you will work on our payment gateway and any other pilot projects towards building the future of KOMOJU. You will work with other engineers in a flat and inclusive culture where engineers have a say in both key product and technology decisions. The culture is largely self-organizing, which means engineers have both a stake and ownership in what they work on. Engineers play to their strengths, but are also able to invest in areas where they want to grow within the team. At KOMOJU, you are the main driver behind your growth and position in the company.

International at our core

Our founder is Canadian, and about 50% of our employees are non-Japanese. In the engineering team, we use English as our common language, and throughout the company, many people are bilingual.

Being an international company we know the importance of bilingualism. We offer all employees a choice between English and Japanese lessons.

About the position

We are looking for a senior backend engineer to help up build our platform to handle payments on a global scale. You will primarily work with Ruby, building out features using Ruby on Rails. As we’re still scaling our front-end team, you may be asked occasionally to work on front-end tasks as well.

As a senior developer, you will need to work with our product managers to define requirements and convert that into a usable architecture to discuss with colleagues. As hiring and supporting new developers is important to us, you will be expected to be able to mentor junior developers, and work with them to improve their core skills.

Our ideal candidate has experience working with large web applications. They will know how to build reliable, scalable, and performant web applications. Testing and code quality are also extremely important to us, so having a strong knowledge of testing and the different testing types is required.

Responsibilities

Understand product goals and feature requests and translate them into working software
Support team members through code review and architecture discussions
Write tests that validate the stability and correctness of implementations
Mentor junior developers and help them grow their skills
Handle refactorings with both bravery and care

Requirements

Experience with building performant and scalable APIs, including DB performance
Experience with integrating with third party APIs in a secure and fault-tolerant manner
Experience and understanding of common web exploits and how to mitigate them
Strong understanding of OOP programming languages and patterns

Nice to Haves

These aren't required, but be sure to mention them in your application if you have them.

Experience with Ruby on Rails
Experience with TypeScript and/or Vue.js
Experience with payments or payment systems
Business-level spoken and written Japanese

Benefits

At Degica, we embrace remote work while also offering office space for those who prefer in-person collaboration
10 days regular vacation, additional 5 days summer and 5 days winter vacation
Paid birthday holiday
Budget for self-learning allowance, to ensure our employees’ skills remain current
Language training for Japanese

APPLY NOW ➜🇯🇵 Residents Only

About KOMOJU

Global payments made simple

KOMOJU is the leading cross-border payment gateway for Japan. They power payments for companies like the video game distribution platform Steam and the popular mobile app TikTok. Today, they help thousands of merchants by providing the payment infrastructure they need, from developer-friendly APIs to integrations on popular platforms like Shopify and Wix. They help merchants grow in all the markets they are expanding into.

Developer-centric, inclusive culture

Engineers at KOMOJU work in a developer-centric and inclusive culture where engineers have a say in both product and technical decisions. The culture is largely self-organizing, which means engineers have both a stake and ownership in what they work on. Engineers play to their strengths, but are also able to invest in areas where they want to grow within the team. At KOMOJU, engineers are the main drivers behind their growth and position in the company.

International at core

Around half of the team members come from outside Japan. English is the primary language used within the engineering team, and throughout the company many people are bilingual.

As an international company, KOMOJU understands the importance of bilingualism. They offer all employees a choice between optional English and Japanese lessons to help create a culture of diversity and ensure smooth collaboration across teams.

Passionate about technology

Developers at KOMOJU are passionate about their craft. To foster innovation, they have a monthly open hack day where developers can work on whatever they want. It could be trying a new programming language or tool, fixing a long-standing annoyance, or something fun and experimental, like building a game.

Japanese Language Policy
With around half of KOMOJU’s total members (and around 90% of engineers) coming from outside Japan, teams generally use English for written communication(e.g. Slack, Github).

Verbal communication is also primarily in English.

However, quite a few people can speak both English and Japanese fluently, so Japanese may be spoken at times during meetings, especially when they involve teams other than engineering.

Overall, the language spoken depends on the team. The dev team uses mostly English, but the HR team (for example) speaks primarily Japanese.
Visa Sponsorship
KOMOJU sponsors visas for candidates living outside of Japan. KOMOJU also helps out with relocation (searching for apartments etc.) but they don’t have a formal policy for this. The support offered depends on each individual case. They do always pay for flight tickets to Japan in the case that someone moves from abroad.
Paid Leave
KOMOJU offers annual leave starting at 10 days, an extra paid holiday on employees’ birthdays, 5 additional vacation days that can be used during the summer months, and another 5 days of year-end holidays.
Benefits
💻 New tech gear

👩‍🎓 Skill development support

💛 Support for attending conferences

💜 Seminar participation support

📕 Book purchases

🍔 Free lunch

🍹 Free drinks

👶 Parental Leave

👩‍🏫 Language Learning Support (Language courses)

💚 Translation support (EN<>JP)

💟 Complete health and social insurance

🚃 Commuter allowance
Engineer Interview Process
Engineering Roles

KOMOJU aims to keep their hiring process thoughtful and efficient. Typically, it involves 3–4 stages depending on the role:
- Initial Screening
- Take-home Exercise
- Technical Interview (Team Interview)
- Final Interview with Leadership
Throughout the process, the team evaluates technical skills and looks for alignment with team culture and potential for long-term growth.
Work style
KOMOJU operates as a remote-first company while placing a strong emphasis on personal connections and close collaboration. The company maintains an office in the Kichijoji area of Tokyo, which employees are welcome to visit for in-person collaboration and company events, such as weekly lunches provided at no cost.

Team members have the flexibility to work from anywhere within Japan, as well as up to three months per year from abroad. KOMOJU also offers flexible scheduling, allowing employees to set their own hours as long as they are available during the company’s core hours, Monday to Friday from 10:00 to 15:00 JST.