Authentication and Authorization Platform Backend Engineer

This position designs, develops, and operates the authentication and authorization platform and the organization and user-management platform on which all KAKEHASHI products depend. The backend engineer works with product managers, designers, and engineers and leads development as a backend specialist.

The platforms include an authentication portal that provides a consistent security and authentication experience across products, a certificate platform supporting more than 1.5 billion mTLS validations per month, and organization and user management for tens of thousands of pharmacies nationwide. Because the products handle medical information, the work addresses high security requirements, including compliance with Ministry of Health, Labour and Welfare guidelines and protection of patient information.

Responsibilities include implementing backend services for authentication and organization management with TypeScript; designing and implementing authentication and authorization flows based on OIDC and OAuth 2.0; designing databases including Aurora PostgreSQL and DynamoDB; building infrastructure based on AWS serverless architecture using ECS, Lambda, and Step Functions; and constructing infrastructure with infrastructure-as-code tools such as Terraform and ecspresso. The role also builds and operates system monitoring with Datadog, performs requirements analysis and specification definition with internal product teams, and conducts technical feasibility studies for large-scale platforms, including a certificate platform with approximately 25,000 certificates and multi-tenant configurations.

Planned technical work includes changing the certificate authority for the certificate platform, making authentication information multi-region, and introducing more secure authentication methods. The team uses AI-driven development, and engineers have discretion to contribute from requirements analysis onward. An onboarding process is provided.

The development organization includes approximately 180 engineers and product managers. Its development environment includes React and TypeScript, and the organization supports sharing information through development blogs, study sessions, and conference presentations.

The stated selection process consists of document screening, a casual interview, two or three interviews, an aptitude test, a reference check using back check, and an offer interview. The reference check collects questionnaire responses from people who worked with the candidate in a current or former job; it is completed online, and KAKEHASHI does not directly contact those references. The process may change depending on circumstances.