CNPJ validator

The brazilian company registry number (Brazil). Validation runs entirely on the check-digit algorithm: two mod-11 check digits with cyclic weights 2-9. No external registry is queried, so there is no rate limit and no per-lookup fee.

Result appears here.

What the API returns

GET /v1/identity/validate?type=cnpj&value=11.222.333/0001-81

{
  "type": "cnpj",
  "valid": true,
  "formatted": "11.222.333/0001-81",
  "details": { ... }
}

Important limitation, stated plainly

A checksum proves the number is well-formed. It does not prove the number was ever issued, nor that it belongs to the person presenting it. Any vendor claiming otherwise from a checksum alone is overselling. Use this to reject the ~90% of bad input that is simply mistyped, then use an official registry for the rest.