Hsuan-Yi Chu developed client certificate authentication for Elasticsearch and OpenSearch within the QuesmaOrg/quesma repository, focusing on enhancing secure connectivity. By integrating TLS mutual authentication, Hsuan-Yi enabled the use of client certificate paths in both configuration and client creation, reducing reliance on traditional credentials and minimizing exposure risks. The implementation required backend development in Go, leveraging skills in API integration, configuration management, and security best practices. This feature streamlined secure deployments by allowing organizations to authenticate connections using certificates rather than passwords. The work demonstrated a solid understanding of secure configuration design and addressed a key security requirement for enterprise environments.