If you build anything in healthcare — a provider directory, a credentialing tool, an EHR integration, or a claims pipeline — sooner or later you need to look up a provider by their NPI (National Provider Identifier) and get back clean, structured data.

In this tutorial we'll do exactly that with the NPI Registry API : look up a provider by NPI, search by name/taxonomy/location, and read the enriched fields it returns (taxonomy, practice locations, Medicare enrollment, PECOS and LEIE flags).

NPI Registry API vs. the free NPPES API. CMS publishes a free NPPES API at npiregistry.cms.hhs.gov — great for light, occasional use, but rate-limited and bare-bones. The commercial NPI Registry API used here adds enrichment (Medicare/PECOS/LEIE, similar providers) and a consistent JSON shape. Full comparison: NPPES API vs. NPI Registry API .

1. Get an API key

Sign up for a free trial and your API key arrives by email in seconds. You authenticate by sending it in an ApiKey header.…