Particle Health supports a RESTful web service based on the FHIR and C-CDA standards. We expose APIs by which verified customers (data seekers) may access health records for over 250M unique patients across the US.
The docs available here will help you get started as a developer using the Particle Health platform. They assume familiarity with web communication tools and protocols, such as HTTP/S. You will need to create an account within our Developer Portal to have access to the tools you'll need, like requesting credentials.