CNPJ

CNPJ is an acronym for "Cadastro Nacional da Pessoa Jurídica," it's a identifier number associated to companies that the Brazilian government maintains. With this number, it is possible to check or retrieve information about a company.

This library provides a validation that checks if the number is a valid CNPJ number. The CPF has check digit algorithm is similar to ISBN 10, you can check the details in Portuguese here.

Installation

If available in Hex, the package can be installed by adding cnpj to your list of dependencies in mix.exs:

def deps do
  [
    {:cnpj, "~> 0.2.0"}
  ]
end

Documentation can be generated with ExDoc and published on HexDocs. Once published, the docs can be found at https://hexdocs.pm/cnpj.

Quick Start

You can verify if a CNPJ is valid by calling the function CNPJ.valid?/1:

CNPJ.valid?("13118061000108")
# => true

CNPJ.valid?("13.118.061/0001-07")
# => false

CNPJ.valid?("12.ABC.345/01DE-35")
# => true

Parsing CNPJS

The CNPJ.parse/1 and CNPJ.parse!/1 returns you the CNPJ value wrapped in a custom type with explicit digits.

CNPJ.parse("70947414000108")
# => {:ok, %CNPJ{digits: "70947414000108"}}

CNPJ.parse("70947414000109")
# => {:error, %CNPJ.ParsingError{reason: :invalid_verifier}}

CNPJ.parse!("70947414000108")
# => %CNPJ{digits: "70947414000108"}

CNPJ.parse!("70947414000109")
# => ** (CNPJ.ParsingError) invalid_verifier

CNPJ Formatting

Create valid CNPJ and in sequence call CNPJ.format/1:

iex> "70947414000108" |> CNPJ.parse!() |> CNPJ.format()
"70.947.414/0001-08"

iex> "12ABC34501DE35" |> CNPJ.parse!() |> CNPJ.format()
"12.ABC.345/01DE-35"

The CNPJ.format/1 expects the CNPJ type.

Alphanumeric CNPJs

Since July 2026 the Receita Federal also issues alphanumeric CNPJs: the first twelve characters can be uppercase letters as well as digits, while the two check digits stay numeric. Existing numeric CNPJs remain valid, and this library accepts both.

The check digits are computed the same way for both formats. Each character is worth its ASCII code minus 48, so digits keep their face value and letters go from A = 17 to Z = 42. Only uppercase letters are accepted, as the Receita Federal specifies.

Migrating to the new format

Integers cannot hold letters, so always pass CNPJs as strings. Integer input still works for numeric CNPJs, but it is deprecated.

# before
CNPJ.valid?(13_118_061_000_108)

# after
CNPJ.valid?("13118061000108")

CNPJ.digits/1 is deprecated as well: it returns integers, so it raises CNPJ.UnsupportedVersionError for a CNPJ with letters. Use CNPJ.digits/2 with the :cnpj_2026 version, which returns strings and works with both formats:

# before
CNPJ.digits(cnpj)
# => {1, 3, 1, 1, 8, 0, 6, 1, 0, 0, 0, 1, 0, 8}

# after
CNPJ.digits(cnpj, :cnpj_2026)
# => {"1", "3", "1", "1", "8", "0", "6", "1", "0", "0", "0", "1", "0", "8"}

If you still need integers for a numeric CNPJ, CNPJ.digits(cnpj, :cnpj_pre_2026) keeps the old behavior.