CNPJ Validation Function

A lightweight, dependency-free PHP library for validating Brazilian CNPJ registration numbers. It accepts compact and formatted values, including the current alphanumeric CNPJ format, and provides both boolean and exception-based APIs.

Requirements

• PHP 8.5 or later

Installation

Install the package with Composer:

composer require cancio-labs/cnpj-validation-function

Composer automatically loads the package functions.

Usage

Import the functions from the CancioLabs\Cnpj\Functions namespace:

use function CancioLabs\Cnpj\Functions\assert_cnpj;
use function CancioLabs\Cnpj\Functions\is_valid_cnpj;

is_valid_cnpj

Use is_valid_cnpj(?string $cnpj): bool when validation should return a boolean result.

use function CancioLabs\Cnpj\Functions\is_valid_cnpj;

is_valid_cnpj('73.078.367/0001-00'); // true
is_valid_cnpj('73078367000100');     // true
is_valid_cnpj('12.ABC.345/01DE-35'); // true
is_valid_cnpj('12ABC34501DE35');     // true

is_valid_cnpj('73.078.367/0001-01'); // false
is_valid_cnpj(null);                 // false

assert_cnpj

Use assert_cnpj(?string $cnpj): void when an invalid CNPJ should stop the current operation. It throws InvalidArgumentException for null, empty, malformed, repeated-digit, or checksum-invalid values.

use function CancioLabs\Cnpj\Functions\assert_cnpj;

assert_cnpj('73.078.367/0001-00');
assert_cnpj('12ABC34501DE35');

// Throws InvalidArgumentException
assert_cnpj('73.078.367/0001-01');

Accepted formats

The first 12 characters may contain uppercase or lowercase letters and digits; letters are normalized to uppercase before validation. The final two check digits must be numeric.

Format	Example
Compact numeric	73078367000100
Formatted numeric	73.078.367/0001-00
Compact alphanumeric	12ABC34501DE35
Formatted alphanumeric	12.ABC.345/01DE-35

How it works

The validator checks the input format, rejects repeated numeric sequences, and verifies both CNPJ check digits. It supports the alphanumeric CNPJ format while preserving compatibility with traditional numeric CNPJs.

Testing

Install development dependencies and run the PHPUnit suite:

composer install
vendor/bin/phpunit tests

Contributing

Contributions are welcome. Please open an issue to discuss substantial changes, then submit a pull request with focused code and accompanying tests.

License

This project is licensed under the GNU General Public License v3.0 or later.