What is the NPI Registry (NPPES)?

"The NPI Registry" and "NPPES" refer to the same thing: the National Plan and Provider Enumeration System, the federal database that issues National Provider Identifiers and publishes a public directory of every enumerated provider in the United States. It's run by the Centers for Medicare & Medicaid Services (CMS), and it's the single source of truth every payer, clearinghouse and EHR ultimately checks against.

Who runs it, and why it exists

NPPES was created under HIPAA's Administrative Simplification provisions to give every healthcare provider — individual or organization — one standard identifier usable across all payers, replacing the tangle of payer-specific provider numbers that existed before. CMS operates the enumeration system; once a provider is assigned an NPI, that number never changes and is never reused, even if the provider retires or the organization closes.

What's public, and what isn't

The NPPES public data file includes: provider name (and any reported "other names"), Type 1/Type 2 status, enumeration date, deactivation status, taxonomy (specialty) codes with license state and number, and practice/mailing addresses with phone. It does not include Social Security numbers, dates of birth, clinical data, or anything about a provider's patients — NPPES is a directory of who providers are, not what they do or who they treat.

Type 1 vs Type 2

• Type 1 (NPI-1) — individual providers: physicians, nurse practitioners, dentists, therapists and other clinicians.
• Type 2 (NPI-2) — organizations: hospitals, group practices, clinics, pharmacies, labs and supplier companies.

How current is it?

NPPES is updated continuously, not on a fixed release cycle — new enumerations, address changes and deactivations post as they happen. CMS also publishes a full monthly data dissemination file, but if you're checking a provider's current status or address, you want the live registry rather than a downloaded snapshot, since it can lag by weeks.

How to search it

CMS's own registry at npiregistry.cms.hhs.gov works, but its interface is dated and it doesn't compose well with other tools — no combined name+taxonomy+geography search in one box, no clean JSON for a script, no history. Patientary's NPI lookup gives you the same underlying data with unified search (name, organization, NPI, taxonomy, location) and a normalized result you can actually read.

For developers and agents

CMS does publish an NPPES API, but it's XML-flavored, undocumented for edge cases, and not designed for agent tool-calling. Patientary wraps the same source data behind a clean REST API (`GET /api/v1/npi/{npi}` and `GET /api/v1/npi?…`) and an MCP server, so an AI agent — or a script — gets a consistent, typed provider record instead of parsing CMS's raw response shape. See the developer docs for the full endpoint reference.