SIREN/SIRET validator
Validate a French SIREN (9 digits) or SIRET (14 digits) number via Luhn.
🔒 100% client-side — no data sent
Check a French SIREN (9 digits) or SIRET (14 digits) number using the Luhn algorithm that validates its check digit. Instantly spot a typo before a declaration or invoice. Calculation runs 100% in your browser: your numbers never leave your device.
What is it for?
- ▸ Check a supplier's SIRET before payment
- ▸ Verify a SIREN entered in a registration form
- ▸ Validate a number shown on a quote or invoice
- ▸ Spot an input error before an administrative filing
FAQ
What is the difference between SIREN and SIRET?
The SIREN (9 digits) identifies the company; the SIRET (14 digits) identifies each establishment by adding a 5-digit NIC code.
How do you check if a SIRET is valid?
You apply the Luhn algorithm: the weighted sum of the digits must be a multiple of 10 for the number to be consistent.
Does this validator check that the company exists?
No, it only checks the mathematical validity of the number, not its actual registration in INSEE's Sirene register.
Is La Poste's head office SIRET an exception?
Yes, La Poste's SIRET numbers do not follow the Luhn key; their validity relies on a specific rule (digit sum being a multiple of 5).