Senior Backend Engineer, ML Platform, Tokyo

Key Highlights

• Design and implement the microservice architecture: a high-performance, low-latency service in Python and FastAPI, built for transaction volumes at the scale of tens of millions of users, including service boundaries and data ownership.
• Design API contracts and reach agreement with stakeholders: OpenAPI schemas and error taxonomies, versioning and backward compatibility, and the process for changing contracts with Digital Bank and group-company stakeholders.
• Bring models and credit logic into production, with resilience by design: the client-side interface for SageMaker endpoints, latency budget allocation, and timeout, retry, circuit breaker, and fallback behavior.
• Implement credit domain logic with correctness and explainability: credit limit calculation with exhaustive boundary and failure cases, idempotency, reproducibility (linking input data, model version, and logic), and audit trail design.
• Design for performance around data supply: how aggregated data in object storage is loaded, freshness management and consistent cutover, caching strategy, and asynchronous/parallel model calls.