Notes NPI to EIN Crosswalk API Documentation NPI to EIN Crosswalk API Documentation Legal Terms of Service Disclaimer Contact Us Privacy Policy Terms of Service This API allows searching U.S. Employer Identification Numbers (EIN) and company records. Responses are JSON encoded. Base Endpoint: https://eintaxid.com/api.php Authentication: Supply your API key via the key query parameter. Request API key ($79 plan) by reaching out to support. Format: JSON (UTF-8). Set header Accept: application/json (optional). Retrieve a single company record by exact EIN (digits only, no dashes). Public example (works only for this EIN without a key): Sample Response:

2. Company Name Search Search by partial or full company name (URL-encode spaces with + or %20 ). Returns up to 10 matches (sample). Public example (works only for this query without a key): Truncated Sample Response (count = 10): Request Parameters * If you are subscribed to $79 plan, you can email us (support@eintaxid.com) to receive api key. Response Fields URL-encode query values. Exact 9-digit numeric query triggers EIN lookup; otherwise treated as name search. Empty fields may be returned as empty strings. Error Handling (Example)