CPF / CNPJ Generator & Validator

The Modulo 11 algorithm, step by step

CPF and CNPJ both use two check digits computed the same way: every position in the document is multiplied by a weight, the products are summed, and the remainder of dividing by 11 gives the expected digit. The Validation tab shows every weight, every product, and the final sum, so you can manually spot exactly where a mistyped document diverges from what's expected.

CPF — weights

weight = position + 1 (counted from the end backward)

CNPJ — weights

weight = (position % 8) + 2, cyclic

The new alphanumeric CNPJ

Since Receita Federal's update, a CNPJ can contain letters as well as digits in its first 12 characters (the two check digits stay numeric). Each letter is turned into a numeric value by the official rule — its ASCII code minus 48 — before entering the same weighted-sum formula used for a traditional CNPJ. Pick 'Alphanumeric CNPJ' in the generator to create examples already in the new format.

The CPF's fiscal region and the CNPJ's branch type

In a CPF, the 9th digit indicates the fiscal region where the document was issued — for example, 8 for São Paulo or 0 for Rio Grande do Sul. Choosing a region in the generator creates documents consistent with that criterion, useful for testing rules that depend on a CPF's origin.

In a CNPJ, digits 9 through 12 indicate the establishment's sequence number: 0001 for headquarters, and following numbers for branches. The generator lets you fix it to headquarters, a branch (a random number other than 0001), or leave it random between the two.

Batch generation for automated testing

Generate up to 50 documents at once, all mathematically valid, and copy the list or download it as a .txt file — useful for populating test spreadsheets, QA data sets, or automated test fixtures without typing each document by hand.

Why documents with all-identical digits are invalid

Sequences like 111.111.111-11 or 00.000.000/0000-00 could even produce mathematically consistent check digits in some cases, but Receita Federal's official rules explicitly invalidate any document with every digit repeated, as an extra safeguard against obvious fraud. The validator rejects these patterns even when the check-digit math works out.