What it does
Paste a number and the type is detected automatically: 11 digits is a TCKN, 10 digits is a VKN, and two letters followed by digits is an IBAN. Every rule is listed with the actual calculation, so you see why a number fails, not just that it does:
- TCKN: 11 digits, first digit not 0, 10th digit = ((d1+d3+d5+d7+d9) × 7 − (d2+d4+d6+d8)) mod 10, 11th digit = sum of the first ten digits mod 10.
- VKN: 10 digits plus the tax-number check digit. A step-by-step table shows each digit’s weighting.
- IBAN: the country length and BBAN format from the SWIFT IBAN Registry (ISO 13616) for all 105 country codes, plus the ISO 7064 MOD 97-10 checksum. You get the expected check digits and the bank and branch fields. Turkish IBANs are split into the 5-digit bank code, the reserve digit and the 16-character account number. Bank names are not looked up.
Bulk, generator and C#
Bulk checks one value per line and exports the results as CSV. Generate creates up to 1,000 distinct synthetic TCKN, VKN or IBAN values, with an optional seed for repeatable fixtures, as a list, JSON or a C# array. C# code gives you IsValidTckn, IsValidVkn and IsValidIban methods that use the same rules as this page, a FluentValidation validator, and xUnit tests.
Generated values are test data only. They pass the checksums but are random, not taken from any real identity or account.
Privacy
Everything runs in your browser and nothing is uploaded. The numbers you check are not stored. Only your settings, such as generator options, are kept in local storage.