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Welcome to Lunar’s API and Developer Resources page, where innovation meets collaboration. We understand the importance of seamless integration and interoperability in today's healthcare landscape, and we're here to empower you with the tools and resources you need to create transformative solutions. Join our thriving developer community and unlock endless possibilities in the realm of healthcare IT.

The API is a read-only HL7 FHIR® R4 REST endpoint. The full specification can be found at

Developer documentation can be found at

To review our API Access Agreement and Terms of Service, click here.


Developers and providers who are interested in accessing the API can register for access by visiting the official website at The registration process allows individuals and organizations to obtain the necessary credentials and permissions to utilize the API and its associated services.

By completing the registration, developers gain access to a range of resources and tools that enable them to integrate the API into their applications, platforms, or services. This includes documentation, code samples, and technical support to assist with the implementation and utilization of the API's features.

The registration process typically involves providing relevant information such as name, email address, organization details, and a brief overview of the intended use case for the API. Upon successful registration, developers and providers will receive the required API keys or authentication tokens, which are essential for establishing secure and authorized connections to the API endpoints.

The platform at serves as a central hub for managing API access, ensuring that developers and providers have the necessary resources and support to leverage the functionality offered by the API.

Connecting to a FHIR Datasource

Client applications can connect to production FHIR data sources enabled by EMR Direct using the FHIR Open API at the following URL:[fhir-version]/[datasource-name]/

The URL immediately above is a FHIR endpoint URL that is used to retrieve resources from the data holder's system. It is not a website that serves HTML for a regular browser like Chrome; instead, it is intended to be accessed by a FHIR client that is following the Interoperability Engine Open API documentation for 3rd party client application developers available at the HealthToGo App Studio site. Information about a variety of additional app registration options is also available there. Developers who are unfamiliar with the SMART user/... clinical scopes may also wish to review this resource. To obtain the datasource-name and supported FHIR version(s), please contact the healthcare organization directly.

Data holders may register for an account used to publish their health data as FHIR resources here:

Determining the baseOAuthURL

The baseOAuthURL is used to access the token, authorization, or registration endpoints. The baseOAuthURL for EMR Direct Interoperability Engine FHIR endpoints is of the form:[datasource-name]/

The baseOAuthURL can be derived from the FHIR endpoint for a given datasource, which is of the form:[fhir-version]/[datasource-name]/

Please contact directly for the datasource-name if it cannot be located in the Interoperability Engine FHIR endpoint directory.

Fees and Value Added Services

Usage of our read-only RESTful HL7 FHIR® R4 API is open to all developers and providers and is free to use. Restrictions, limitations, and obligations can be found here.

Lunar does not currently offer value-added-services for developers. However, we are working on a developer marketplace, so please check back soon! Please direct questions to

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