This plugin adds server-side validation for Brazilian CPF (individual taxpayer) and CNPJ (company taxpayer) identification numbers within contact forms. It is designed for website administrators in Brazil who need to collect and verify these official IDs from users. The validation checks the number's format and official calculation algorithm to ensure submitted data is structurally correct before form submission.

• Server-side validation: All checks are performed on the server. This method is reliable and does not rely on client-side JavaScript, which can be bypassed.
• Non-intrusive integration: The plugin works by detecting specific CSS classes added to form fields. It does not alter your site's layout or require complex configuration.
• Independent field validation: You can validate CPF fields, CNPJ fields, or both within the same form. The validation logic for each ID type is applied independently.
• Works with optional fields: Validation is applied to both required and optional text fields, providing flexibility in form design.
• Backward compatibility: The plugin is tested for compatibility with a wide range of versions of the underlying contact form plugin.