🇫🇷SIREN / SIRET Validator (France)

SIREN / SIRET validator — check a French company number online

Our free SIREN and SIRET validator instantly verifies the validity of a French business identification number. The tool automatically detects whether a 9-digit SIREN or a 14-digit SIRET has been entered, then checks the check digit using the Luhn algorithm (mod 10). Spaces are ignored, so you can paste numbers in any format.

The validator handles the historical exception for La Poste (SIREN 356000000), which does not satisfy the standard Luhn algorithm but is legally valid. For SIRET numbers, the extracted SIREN (first 9 digits) and NIC (last 5 digits) are also displayed, making it easy to identify a specific branch of a company.

Full privacy — local processing

All verification takes place entirely in your browser. Not a single digit you enter is sent to any server. You can use the validator even offline, and the numbers you enter remain solely on your device.

Frequently asked questions

What is a SIREN number?

SIREN (Systeme d'Identification du Repertoire des ENtreprises) is a 9-digit identifier assigned to every company or self-employed person in France by the INSEE institute. It uniquely identifies a business entity in state registers.

How does SIRET differ from SIREN?

SIRET (Systeme d'Identification du Repertoire des ETablissements) is a 14-digit number that identifies a specific business location (establishment). It consists of the 9-digit SIREN of the company and a 5-digit NIC code (Numero Interne de Classement) that distinguishes individual branches of the same company.

How does the Luhn algorithm used to validate SIREN and SIRET work?

The Luhn algorithm (mod 10) sums up the digits of the number according to the following rule: starting from the right, every second digit is multiplied by 2, and if the result exceeds 9, 9 is subtracted. If the total sum is divisible by 10, the number is valid. This algorithm is widely used to verify payment card numbers and many administrative identifiers.

Why is La Poste's SIREN (356000000) an exception?

The SIREN 356000000 assigned to La Poste (the French postal service) does not satisfy the Luhn algorithm, yet it is a legally valid and universally recognised number in INSEE registers. It is a historical exception arising from early numbering rules, so validators should treat it as valid.

Does SIREN/SIRET validation guarantee that the company exists?

No. Checking the Luhn checksum only confirms the mathematical correctness of the number. It does not verify whether the company is active or has been removed from the register. For up-to-date information, consult official databases such as Infogreffe or the INSEE portal.

Is my data sent to a server?

No. All verification is performed locally in your browser. Not a single character you enter is sent to any server. You can validate numbers even without an internet connection.