One of CartoChrome's core design principles is that the platform runs entirely on free, publicly available data. No paid data licenses, no Data Use Agreements that take months to negotiate, no proprietary datasets that could disappear or change terms. Every byte of data that powers our Healthcare Access Scores comes from federally maintained, publicly documented sources with stable APIs or automated download endpoints.
Here is the complete inventory of all 21 data sources, organized by what they provide.
Provider Data (2 Sources)
**1. CMS NPPES (National Plan and Provider Enumeration System)** -- This is the foundation of our provider directory. The NPI registry contains approximately 7.5 million records, which we filter to ~4 million active, patient-facing providers. Updated monthly with a full file download and weekly delta files for incremental updates. Every physician, nurse practitioner, physician assistant, dentist, and other healthcare provider with an NPI number appears here with their practice address, specialty taxonomy codes, and organizational affiliations.
**2. CMS Doctors and Clinicians (Physician Compare)** -- Supplements NPPES with quality measures, Medicare acceptance status, and group practice affiliations. This data allows us to distinguish between a provider who technically has an NPI and one who is actively seeing patients and accepting common insurance.
Facility Data (5 Sources)
**3. CMS Provider of Services (POS)** -- The master list of Medicare-certified hospitals and healthcare facilities, including bed counts, ownership type, services offered, and accreditation status. This powers our Hospital Inpatient access component.
**4. CMS Hospital Compare** -- Star ratings, mortality rates, readmission rates, patient experience scores (HCAHPS), and safety indicators for every Medicare-certified hospital. We use these quality metrics to weight facilities in our scoring algorithm -- a 5-star hospital contributes more to access than a 1-star facility at the same distance.
**5. CMS Care Compare** -- Quality data for nursing homes, home health agencies, and dialysis facilities. Extends our facility coverage beyond hospitals to include the long-term and specialized care facilities that are critical for chronic disease management.