cnpj-dv 2.0.0

🚀 Full support for the new alphanumeric CNPJ format.

🌎 Acessar documentação em português

A Python utility to calculate check digits on CNPJ (Brazilian Business Tax ID).

Python Support

Passing ✔	Passing ✔	Passing ✔	Passing ✔	Passing ✔

Features

• ✅ Alphanumeric CNPJ: Full support for the new alphanumeric CNPJ format (introduced in 2026)
• ✅ Flexible input: Accepts str or list[str]
• ✅ Format agnostic: Strips non-alphanumeric characters from string input and uppercases letters
• ✅ Auto-expansion: Multi-character strings in lists are joined and parsed like a single string
• ✅ Input validation: Rejects ineligible CNPJs (all-zero base ID 00000000, all-zero branch 0000, or 12 numeric-only repeated digits)
• ✅ Lazy evaluation: Check digits are calculated only when accessed (via properties)
• ✅ Caching: Calculated values are cached for subsequent access
• ✅ Type hints: Built with Python 3.10+ type annotations
• ✅ Minimal dependencies: Only lacus.utils
• ✅ Error handling: Specific types for type, length, and invalid CNPJ scenarios (TypeError vs Exception semantics)

Installation

$ pip install cnpj-dv

Quick Start

from cnpj_dv import CnpjCheckDigits

Basic usage:

check_digits = CnpjCheckDigits("914157320007")

check_digits.first   # '9'
check_digits.second  # '3'
check_digits.both    # '93'
check_digits.cnpj    # '91415732000793'

With alphanumeric CNPJ (new format):

check_digits = CnpjCheckDigits("MGKGMJ9X0001")

check_digits.first   # '6'
check_digits.second  # '8'
check_digits.both    # '68'
check_digits.cnpj    # 'MGKGMJ9X000168'

Usage

The main resource of this package is the class CnpjCheckDigits. Through an instance, you access CNPJ check-digit information:

• __init__: CnpjCheckDigits(str | list[str]) — 12–14 alphanumeric characters after sanitization (formatting stripped from strings; letters uppercased). Only the first 12 characters are used as the base; if you pass 13 or 14 characters (e.g. a full CNPJ including prior check digits), characters 13–14 are ignored and the digits are recalculated.
• first: First check digit (13th character of the full CNPJ). Lazy, cached.
• second: Second check digit (14th character of the full CNPJ). Lazy, cached.
• both: Both check digits concatenated as a string.
• cnpj: The complete CNPJ as a string of 14 characters (12 base characters + 2 check digits).

Input formats

The CnpjCheckDigits class accepts multiple input formats:

String input: raw digits and/or letters, or formatted CNPJ (e.g. 91.415.732/0007-93, MG.KGM.J9X/0001-68). Non-alphanumeric characters are removed; lowercase letters are uppercased.

List of strings: each element must be a string; values are concatenated and then parsed like a single string (e.g. ["9","1","4",…], ["9141","5732","0007"], ["MG","KGM","J9X","0001"]). Non-string elements are not allowed.

# String — plain, formatted, or with existing check digits (only first 12 chars used)
CnpjCheckDigits("914157320007")
CnpjCheckDigits("91.415.732/0007")
CnpjCheckDigits("91415732000793")

# List of strings — single- or multi-character elements
CnpjCheckDigits(["9", "1", "4", "1", "5", "7", "3", "2", "0", "0", "0", "7"])
CnpjCheckDigits(["9141", "5732", "0007"])
CnpjCheckDigits(["MG", "KGM", "J9X", "0001"])

Errors & exceptions handling

This package uses TypeError vs Exception semantics: type errors indicate incorrect API use (e.g. wrong type); exceptions indicate invalid or ineligible data (e.g. invalid length or business rules). You can catch specific classes or use the base classes.

• CnpjCheckDigitsTypeError — base class for type errors; extends Python's TypeError
• CnpjCheckDigitsInputTypeError — input is not str or list[str] (or list contains a non-string element)
• CnpjCheckDigitsException — base class for data/flow exceptions; extends Exception
• CnpjCheckDigitsInputLengthException — sanitized length is not 12–14
• CnpjCheckDigitsInputInvalidException — base ID 00000000, branch ID 0000, or 12 identical numeric digits (repeated-digit pattern)

from cnpj_dv import (
    CnpjCheckDigits,
    CnpjCheckDigitsException,
    CnpjCheckDigitsInputInvalidException,
    CnpjCheckDigitsInputLengthException,
    CnpjCheckDigitsInputTypeError,
)

# Input type (e.g. integer not allowed)
try:
    CnpjCheckDigits(12345678000100)
except CnpjCheckDigitsInputTypeError as e:
    print(e)  # CNPJ input must be of type string or string[]. Got integer number.

# Length (must be 12–14 alphanumeric characters after sanitization)
try:
    CnpjCheckDigits("12345678901")
except CnpjCheckDigitsInputLengthException as e:
    print(e)  # CNPJ input "12345678901" does not contain 12 to 14 characters. Got 11.

# Invalid (e.g. all-zero base or branch, or repeated numeric digits)
try:
    CnpjCheckDigits("000000000001")
except CnpjCheckDigitsInputInvalidException as e:
    print(e)  # CNPJ input "000000000001" is invalid. Base ID "00000000" is not eligible.

# Any data exception from the package
try:
    CnpjCheckDigits("000000000001")
except CnpjCheckDigitsException as e:
    print(e)

Other available resources

Import from cnpj_dv:

• CNPJ_MIN_LENGTH: 12
• CNPJ_MAX_LENGTH: 14
• Exceptions: see above

Calculation algorithm

The package computes check digits with the official Brazilian modulo-11 rules extended to alphanumeric characters:

1. Character value: each character contributes ord(character) − 48 (so 0–9 stay 0–9; letters use their ASCII offset from 0).
2. Weights: from right to left, multiply by weights that cycle 2, 3, 4, 5, 6, 7, 8, 9, then repeat from 2.
3. First check digit (13th position): apply steps 1–2 to the first 12 base characters; let r = sum % 11. The digit is 0 if r < 2, otherwise 11 − r.
4. Second check digit (14th position): apply steps 1–2 to the first 12 characters plus the first check digit; same formula for r.

Contribution & Support

We welcome contributions! Please see our Contributing Guidelines for details. If you find this project helpful, please consider:

• ⭐ Starring the repository
• 🤝 Contributing to the codebase
• 💡 Suggesting new features
• 🐛 Reporting bugs

License

This project is licensed under the MIT License — see the LICENSE file for details.

Changelog

See CHANGELOG for a list of changes and version history.

Made with ❤️ by Lacus Solutions