medical.npi

Look up US healthcare providers in the CMS NPPES registry — the authoritative directory of National Provider Identifiers (NPIs). Give an exact 10-digit NPI, or search by provider last name (+ optional first name), or organization name, optionally narrowed by state and taxonomy/specialty. Returns each provider with NPI, entity type (individual vs organization), status, name/credential/gender or organization name, sole-proprietor flag, enumeration + last-updated dates, primary taxonomy, the full taxonomy list (code, description, primary flag, state license), and practice/mailing addresses with phone. Free, public-domain (CMS). The canonical "who is this NPI / find this provider" lookup for healthcare, claims, and credentialing agents.

price
$0.0011 USDC per call
method
GET/api/medical/npi
payment
x402 v2 · USDC on Base (EIP-3009) or Solana (SPL transfer)
auth
None. Sign the payment, retry with PAYMENT-SIGNATURE.

Overview

The npi API is a pay-per-call medical endpoint built for AI agents and autonomous software. Look up US healthcare providers in the CMS NPPES registry — the authoritative directory of National Provider Identifiers (NPIs).

There is no signup and no API key. An agent (or any HTTP client) hits the endpoint, receives an x402 "402 Payment Required" challenge, signs a sub-cent USDC payment on Base or Solana, and retries — the data comes back on the paid request. That makes it a drop-in npi data source for an agent tool-use loop, an MCP host, or a backend that needs medical data on demand without onboarding to yet another vendor portal.

Use cases

Parameters

NameTypeDescription
npistring
match ^\d{10}$
firstNamestring
min 1 chars · max 60 chars
lastNamestring
min 1 chars · max 60 chars
organizationstring
min 2 chars · max 120 chars
statestring
min 2 chars · max 2 chars
taxonomystring
min 2 chars · max 80 chars
limitinteger
min 1 · max 50

Code samples

cURLbash
# 1. Probe with no auth → 402 envelope with PaymentRequirements
curl -sS 'https://2s.io/api/medical/npi?npi=12345&firstName=example&lastName=example&organization=xx&state=xx&taxonomy=xx&limit=1'

# 2. Sign + retry with PAYMENT-SIGNATURE:
curl -sS 'https://2s.io/api/medical/npi?npi=12345&firstName=example&lastName=example&organization=xx&state=xx&taxonomy=xx&limit=1' \
  -H 'PAYMENT-SIGNATURE: <base64-json-payload>'

# Or use the canonical runner (handles probe → sign → retry):
#   EVM_PRIVATE_KEY=0x... node --env-file=.env.local \
#     --experimental-strip-types scripts/x402-pay.ts \
#     'https://2s.io/api/medical/npi?npi=12345&firstName=example&lastName=example&organization=xx&state=xx&taxonomy=xx&limit=1'
TypeScript / Node — @2sio/sdktypescript
import { TwoS } from '@2sio/sdk'

const client = new TwoS({
  privateKey: process.env.EVM_PRIVATE_KEY as `0x${string}`,
})

const result = await client.medical.npi({
  "npi": "12345",
  "firstName": "example",
  "lastName": "example",
  "organization": "xx",
  "state": "xx",
  "taxonomy": "xx",
  "limit": 1
})

console.log('endpoint:', result.endpoint)
console.log('cost:', result.costUsd, 'USDC')
console.log('tx:', result.settlement?.txHash)
console.log('data:', result.data)
Python — 2siopython
import os
from twosio import TwoS

client = TwoS(private_key=os.environ["EVM_PRIVATE_KEY"])

result = client.medical.npi(npi="12345", firstName="example", lastName="example", organization="xx", state="xx", taxonomy="xx", limit=1)

print("endpoint:", result.endpoint)
print("cost:", result.cost_usd, "USDC")
print("tx:", (result.settlement or {}).get("tx_hash"))
print("data:", result.data)
MCP — Claude Desktop / AgentKit / any MCP hostjson
// 1. Add @2sio/mcp to your MCP host config (Claude Desktop example below).
//    EVM_PRIVATE_KEY funds x402 payments per call.

// claude_desktop_config.json
{
  "mcpServers": {
    "2sio": {
      "command": "npx",
      "args": ["-y", "@2sio/mcp"],
      "env": { "EVM_PRIVATE_KEY": "0x..." }
    }
  }
}

// 2. Once the server is running, agents call this tool via standard MCP:

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "medical.npi",
    "arguments": {
      "npi": "12345",
      "firstName": "example",
      "lastName": "example",
      "organization": "xx",
      "state": "xx",
      "taxonomy": "xx",
      "limit": 1
    }
  }
}

Response

FieldTypeDescription
okboolean
one of: true
itemsarray
totalintegerTotal matching rows upstream; null when unknown.
sourceobject
Example response datajson
{
  "ok": true,
  "items": [
    {
      "npi": "example",
      "enumerationType": "example",
      "entityType": "Individual",
      "status": "example",
      "firstName": "example",
      "lastName": "example",
      "credential": "example",
      "gender": "example",
      "organizationName": "example",
      "soleProprietor": "example",
      "enumerationDate": "example",
      "lastUpdated": "example",
      "primaryTaxonomy": "example",
      "taxonomies": [
        {
          "code": "example",
          "description": "example",
          "primary": false,
          "state": "example",
          "license": "example"
        }
      ],
      "addresses": [
        {
          "purpose": "example",
          "address1": "example",
          "address2": "example",
          "city": "example",
          "state": "example",
          "postalCode": "example",
          "countryCode": "example",
          "telephone": "example",
          "fax": "example"
        }
      ]
    }
  ],
  "total": 1,
  "source": {
    "provider": "example",
    "url": "example",
    "license": "example"
  }
}

FAQ

Do I need an API key to use the npi API?
No. medical.npi is x402-native — there is no signup and no API key. Your client makes the call, receives a 402 with payment requirements, signs a USDC payment, and retries. Funds come from a wallet you control.
How much does the npi API cost?
$0.00108 USDC per call, charged per request. There are no monthly fees, seats, or minimums — you pay only for the calls you make.
Can I try the npi API for free first?
Yes. Add ?trial=1 (or the header X-2s-Trial: 1) to get a free real call per endpoint per hour, so you can verify the response shape before wiring payment.
Which networks and tokens are supported?
USDC on Base (via EIP-3009 transferWithAuthorization) or Solana (SPL transfer), using the open x402 payment protocol.
How do I call medical.npi from an AI agent or MCP host?
Use @2sio/sdk (TypeScript), 2sio (Python), or the @2sio/mcp server for any MCP host — each handles the probe → sign → retry loop for you. See the code samples on this page.

Discovery

Related: npi api · medical npi api · npi api for ai agents · x402 medical api · npi api no api key · pay per call npi api · medical api