New York City's healthcare ecosystem is uniquely complex. Hundreds of hospitals, thousands of physician practices, dozens of specialty networks, and one of the country's largest regional health information organizations — Healthix — create an interoperability environment that demands precise, well-tested HL7 interface development. Zerosums Technologies provides HL7 integration services tailored to NYC's specific systems and exchange patterns. Our engineers build HL7 v2 interfaces, FHIR R4 APIs, and CDA documents that connect Epic, Cerner Millennium, MEDITECH, athenahealth, eClinicalWorks, and dozens of specialty applications. We work with all major integration engines — Mirth Connect, InterSystems HealthShare, Rhapsody, and Cloverleaf — and select the right tool for each client's environment. For NYC organizations participating in Healthix, we support the full technical onboarding process: ADT event notification interfaces, C-CDA document submission, query-based exchange configuration, and ongoing monitoring. Healthix connectivity enables care coordination across NYC's fragmented care continuum, and we help organizations get connected and stay connected. We also develop NYC-specific integrations including interfaces with city laboratory networks, NYC DOHMH reporting systems, Medicaid EHR incentive program connections, and the data exchange infrastructure supporting NYC's public health initiatives.