Fullstack Web Developer

  • Tokyo
  • No Remote
  • Full-time
  • November 30, 2022
6,000,000 - 8,000,000 JPY /yr
Apply from Japan Only
No relocation to Japan
(No visa sponsorship from overseas)
Language Requirements
Japanese: Not Required 👍
English: Business Level
Minimum Experience
Mid-level or above

At pafin (formerly known as Cryptact) we are building an innovative platform where patients can share their medical images (such as MRI, CT and X-ray) with clients in the AI sector via blockchain technology. The aim is to help our AI clients increase the speed and accuracy of detecting illnesses by providing them with comprehensive datasets.

We are looking for an engineer that can help build and launch the solution. The candidate will closely work with stakeholders and will be part of developing this new business, not only from system implementation but also the business processes alongside other team members.

We are working in collaboration with the University of Tokyo Hospital and SoftBank (See Press Release )

As an engineer in the team, they will be actively engaged in discussions with stakeholders about the business model and requirements, system architecture and design, implementation strategies and so on. A prototype of the solution was extremely well received by stakeholders and we are in the early stages of creating a production-ready version of that, so this a chance to get involved at the beginning and help to shape the direction of the solution.


  • 3+ years of professional full-stack web development experience using JavaScript and/or TypeScript, HTML and CSS, and React
  • Good analytical and problem solving abilities
  • Excellent communication skills and capable of working with both technical and non-technical people
  • Having an intellectual maturity and capability to cope with changing requirements as is often observed in a start-up environment
  • Business level English (reading, writing and speaking)

Preferred Qualifications

  • Backend experience e.g. Python
  • Databases e.g. PostgreSQL
  • Cloud environments e.g. AWS
  • Experience with blockchain technology and smart contracts
  • Experience in the medical imaging sector
  • Knowledge of security and cryptography
  • Good understanding of data privacy and protection laws in Japan and other regions of the world
  • Experience with machine learning
  • Japanese proficiency


  • Annual salary of ¥6m to ¥8m with stock options available

pafin (formerly Cryptact) is a Fintech start-up whose platform enables you to manage all of your investments in one place — from stocks to cryptocurrency.

Their cryptact service was released in 2017 and is Japan’s largest when it comes to calculating cryptocurrency taxes. Their service also supports US and overseas accounting methods with plans for professionals as well.

They also run fintact, a service that helps people around the world find investment ideas and information. It is designed from the ground up to ensure transparency while providing a rich game-like experience within a large global community of investors.

View pafin's company page

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Fullstack Web Developer at pafin
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