Worked on security hardening and data privacy improvements for the companieshouse/psc-data-api repository, focusing on backend development and API data transformation. Addressed the risk of internal identifier leakage by modifying the IndividualFullRecord transformation to exclude internal_id fields from API responses, ensuring sensitive data remained protected. Patched a known security vulnerability by upgrading the Spring Boot starter dependency, maintaining system stability without requiring code changes. Utilized Java for backend logic and applied best practices in dependency management and NULL field handling. The work enhanced compliance and privacy posture while validating existing data paths and tests to ensure continued reliability of the API.