Developed and integrated UK Government Energy Performance Certificates (EPC) API support within the NangoHQ/nango repository, enabling secure data retrieval through API Key authentication and Bearer token flows. Focused on backend development and API integration using TypeScript and YAML, the work established a migration-ready foundation for retiring the legacy EPC service, with detailed migration notes and a deprecation timeline to ensure minimal customer disruption. Collaborated closely with other contributors, providing comprehensive documentation and testing instructions to facilitate future maintenance. The implementation emphasized robust error handling and standardized authentication, enhancing both the reliability and security of production data flows across teams.