NPI Number Validator
Paste a 10-digit National Provider Identifier and we'll verify it against the CMS-published Luhn check. Free, runs entirely in your browser. No login, no logs, no tracking of what you check.
An NPI is a 10-digit numeric identifier issued by CMS. The 10th digit is a Luhn check digit derived from the first 9 plus the constant prefix 80840.
What this checks
The CMS NPI specification uses a slightly modified Luhn algorithm. The constant 80840 is prepended to the 10-digit NPI, then standard Luhn is applied. The 10th digit of the NPI is a check digit chosen so the whole 15-digit sequence passes Luhn.
A valid result means the number is syntactically a real NPI shape. It does not mean the provider is currently active, in good standing, or enrolled with payers — for that, look up the NPI in our directory or in NPPES directly.
How to verify a provider beyond the check digit
- Check the NPI is valid here.The Luhn check confirms the number is well-formed.
- Look it up in our directory.Praxis MD mirrors NPPES with monthly + weekly refreshes; search by NPI, name, or specialty.
- Confirm the state license is currently active.NPI presence is not proof of licensure. State licensing boards publish current status.
- Confirm payer enrollment if billing.Medicare PECOS and commercial payer directories are the authoritative sources.
Need to validate hundreds of NPIs at once?
Praxis MD's email-gated bulk lookup handles 50 at a time. For a larger validated CSV with verified contact data, request a custom list from Provyx.
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