# SIREN Number Lookup > Check a French SIREN number and see where the company behind it is confirmed. Canonical: https://corpoapi.com/checks/siren-check Type a SIREN and the check reports whether it is nine digits with a valid Luhn check digit. It reads the number, not the register. INSEE, which issues SIREN numbers, is where the company is confirmed. ## What the check reads - **Nine digits** The count runs after spaces and dots are stripped. A SIRET adds five digits for one establishment, so a fourteen-digit number fails here as a SIREN. - **The Luhn check digit** The last digit is computed by the Luhn rule over the first eight. If the recomputed digit does not match, the number is not well formed, which usually means a transposed pair. - **Spaces and dots** The number is often written in groups, as in 303 265 045. Separators are formatting only, so the check ignores them. - **SIREN and SIRET** The SIREN is the nine-digit entity number. The SIRET is the SIREN plus five digits for one premises. A SIRET passes only its first nine digits, which are the SIREN. - **What this does not check** Whether the number was issued, which company holds it, and whether it is still active. INSEE holds all of that in the SIRENE register. ## Where the data comes from - [INSEE](https://www.insee.fr/): The French statistics institute that holds the SIRENE register and issues SIREN numbers. - [Annuaire des entreprises](https://annuaire-entreprises.data.gouv.fr/): The public company directory built on the SIRENE register, for confirming a SIREN or SIRET. ## Worked examples ### A well-formed SIREN Input: `303265045` - **SIREN**: 303265045 - **Digits**: 9 - **Luhn check digit**: Matches - **Verdict**: Well formed - **Where to confirm**: INSEE Sirene SA SODIMAS carries this SIREN in the French register. Passing here says the digits are well formed; INSEE is where the company behind the SIREN is confirmed. ### Two digits transposed Input: `303265054` - **Digits**: 9 - **Luhn check digit**: Does not match - **Verdict**: Not well formed - **Likely cause**: Two digits transposed or one mistyped Swapping the last two digits breaks the Luhn sum, so the number cannot be a real SIREN. ### One digit short Input: `30326504` - **Digits**: 8 - **Needed**: 9 - **Verdict**: Not a SIREN A SIREN is nine digits, so an eight-digit input is short by one. A fourteen-digit SIRET fails here too and should be trimmed to its first nine digits. ## Nine digits and a Luhn check digit A SIREN is nine digits and identifies a French legal entity. The last digit is a check digit computed by the Luhn rule. The check strips spaces and dots, counts the digits and recomputes the check digit. A SIRET adds five digits for one establishment and starts with the SIREN. - Nine digits, spaces and dots ignored - Luhn check digit recomputed - SIREN and SIRET told apart ## A well-formed SIREN is not a company The check runs in your browser and never contacts INSEE. Nine digits with a valid check digit prove the number is well formed, and that is all. They do not prove the company exists, is still active, or is the one on your invoice. INSEE is the authority for that. - A valid number does not prove a company exists - Status and filings live in the register - The check never reaches INSEE ## INSEE issues the number INSEE holds the SIRENE register, the source of every SIREN and SIRET. The public company directory lets you search by number or name and returns the entity, its status and its establishments. Our free company search reaches the register too. - Search the number in the company directory - See the entity and its establishments - Search by name with the free company search ## FAQ ### Does this find the company behind a SIREN? No. The check reads the format of the number. INSEE holds the SIRENE register, and the public company directory at annuaire-entreprises.data.gouv.fr returns the entity, its status and its establishments for a SIREN. ### Does a valid SIREN prove the company exists? No. A valid format means nine digits with a matching check digit. It does not prove the number was issued, that a company is registered under it, or that it is still active. Only INSEE can say. ### What is the difference between a SIREN and a SIRET? A SIREN is the nine-digit number for the legal entity. A SIRET is the SIREN plus five digits that identify one establishment or premises. A company has one SIREN and can have many SIRETs. ### Why does my number fail the check digit? The last digit is computed from the first eight. A failure usually means two digits were transposed or one was mistyped. Recheck the number against the SIRENE register. ### Can I look up a company by name instead? Yes. The free company search matches names fuzzily against the French register and returns the closest candidates with their SIREN, status and address. ### Is the check free? Yes. It costs nothing and asks for no account. A mistyped SIREN is caught by the browser-side check digit before any allowance is spent, and a well-formed one uses one of the tool's 5 daily checks.