Company number validator (BCE / SIREN / SIRET)
Validate a Belgian BCE number (modulo 97) or a French SIREN and SIRET (Luhn algorithm), and read off the matching VAT number. It is the quick sanity check before you trust a partner, print a letterhead or register a customer. You enter a public company identifier; the check happens on your device, so a partner list never leaves your screen.
- 100% local
- Free · no account
- Instant result
This tool runs entirely in your browser — nothing is sent to a server.
In Belgium, every company is issued a 10-digit enterprise number registered at the Crossroads Bank for Enterprises (KBO/BCE), which also forms the basis of the VAT number (prefixed with BE). In France, INSEE assigns a 9-digit SIREN to each company and a 14-digit SIRET to each establishment.
This tool automatically detects the type of number entered, verifies its check digit (modulo 97 for KBO/BCE, Luhn algorithm for SIREN and SIRET) and derives the corresponding VAT number.
How it works
Type the figures or drop the file you want to process — the tool checks them as you go.
Everything is computed directly in your browser. Nothing is sent to a server.
The result appears instantly, with the detailed breakdown ready to copy, download or keep.
Why use this tool
No account, no download, no limit: the result appears as soon as you enter your data.
Every rule, algorithm and check reflects what we use ourselves every day at Flexina.
The calculations follow the official standards, and the step-by-step detail lets you double-check the outcome.
What does running it locally bring you?
Files, figures and documents never leave your device: nothing is stored, nothing is sent.
Once the page is loaded, you can cut the network: the tool keeps working.
No upload, no account, no third-party server in between: results stay fast and fully private.
Frequently asked questions
What is the difference between SIREN and SIRET?
The SIREN (9 digits) identifies the company; the SIRET (14 digits) identifies each of its establishments. SIRET = SIREN + 5-digit NIC.
How do I go from a KBO/BCE number to a Belgian VAT number?
Just add the BE prefix before the 10 digits: company 0403.200.393 has VAT number BE0403200393 (if it is VAT-registered).
Does a valid number mean the company exists?
No, only that the check digit is correct. To verify existence, consult the KBO/BCE (Belgium), the company directory (France) or the VIES service for VAT.