credit_cat

credit_cat is a Dart library for validating and identifying credit card numbers. It validates using the Luhn algorithm and length checking, identifies the card issuer, and determines the industry category.

Supported Issuers

Visa, Mastercard, American Express, Discover, Diners Club, JCB, UnionPay, Maestro

Overview

import 'package:credit_cat/credit_cat.dart';

void main() {
  final cat = CreditCat("378282246310005");

  // Validation (Luhn + length check)
  print(cat.isValid); // true

  // Card identification
  print(cat.issuer); // Issuers.amex
  print(cat.industry); // Industries.travelAndEntertainment

  // Display helpers
  print(cat.maskedNumber); // ***********0005
  print(cat.formattedNumber); // 3782 822463 10005
}

Features

Validation

isValid checks both the Luhn checksum and that the card length is correct for the detected issuer.

final valid = CreditCat("4111111111111111");
print(valid.isValid); // true (valid Luhn + 16 digits for Visa)

final invalidLength = CreditCat("41111111111111"); // 14 digits
print(invalidLength.isValid); // false (Visa requires 13, 16, or 19 digits)

You can also check components separately:

• isLuhnValid - Luhn checksum only
• isValidLength - length validation only

Input Cleaning

credit_cat automatically removes spaces and dashes from the input:

final cat = CreditCat("4111-1111-1111-1111");
print(cat.number); // 4111111111111111

You can also provide a custom regex for cleaning:

final cat = CreditCat("4111.1111.1111.1111", RegExp(r"\."));
print(cat.number); // 4111111111111111

Display Helpers

final cat = CreditCat("4111111111111111");

// Masked for receipts/display
print(cat.maskedNumber); // ************1111

// Formatted with spaces (Amex uses 4-6-5, others use 4-4-4-4)
print(cat.formattedNumber); // 4111 1111 1111 1111