Fake NPI Generator for Testing
Generate synthetic, checksum-valid NPI numbers in one click — realistic 10-digit NPIs that pass the CMS Luhn checksum for development, QA, training, and demos. Bulk generation up to 100 with CSV export. Free, no signup, nothing stored.
For testing only. These NPIs are randomly generated and not issued by CMS. Never use them on a real claim or any HIPAA-covered transaction.
Generated in your browser — nothing is sent to or stored on our servers.
How fake NPIs are generated
Every NPI is a 10-digit number whose final digit is a Luhn (ISO/IEC 7812) check digit computed over the first 9 digits, prefixed with 80840 — the CMS issuer identifier for the US health-industry range. This generator follows the exact same construction CMS uses, so every number passes the checksum your billing software runs.
- First digit 1 (individual / NPI-1) or 2 (organization / NPI-2) — the CMS-assigned ranges
- 8 random digits fill positions 2–9
- 10th digit computed via Luhn over '80840' + first 9 digits
- Uniqueness guaranteed within every batch
# Generating one fake NPI 1. Pick first digit: 1 or 2 2. Add 8 random digits → e.g. 123456789 3. Prefix with '80840' → 80840 123456789 4. Double alternating digits (Luhn) 5. check = (10 - (sum mod 10)) mod 10 → 3 6. Result: 1234567893 → passes CMS checksum ✓ → not in NPPES (synthetic)
A valid checksum only means the number is well-formed. To check whether an NPI is real, run it through our NPI Validator — it confirms checksum and live NPPES registry status in one call.
Realistic test data, zero compliance risk
Development & QA
Populate dev and staging databases, test 837 / EDI generation, and run clearinghouse onboarding without touching real provider identities.
Pipeline testing
Feed checksum-valid NPIs through extraction, validation, and adjudication pipelines so format checks behave exactly like production.
Training & demos
Teach billing staff and demo products with realistic-looking NPIs — keeping PHI and real provider identifiers out of classrooms and screenshots.
Pair this with Hewto.ai's NPI Validator and NPI Lookup by Name to round out your test-data toolkit — generate synthetic NPIs here, verify real ones there.
Common questions about test NPI numbers
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