The Kodjin FHIR server is an ONC-certified and HIPAA-compliant solution designed for large-scale healthcare systems, handling tens of millions of patient records and thousands of requests per second. Built with a modern tech stack including Rust, Kafka, and Kubernetes, the system utilizes MongoDB as its transactional data store, providing flexible schema and multi-document transactions to ensure data consistency and integrity. Additionally, GridFS is employed for efficient storage and retrieval of terminologies, enhancing the functionality of the Terminology service. The system has demonstrated high performance in various scenarios, including GET by ID, search, and POST operations, with values exceeding 1700 requests per second, showcasing its ability to handle significant workloads and provide timely access to resources.