Credit Card Validator

Credit card validation is a critical process in e-commerce and financial software. But how does a system know if a number is real before even sending it to a bank? The answer lies in a mathematical formula known as the Luhn Algorithm (or Modulus 10 algorithm).

The Luhn Algorithm Explained

The Luhn algorithm is a simple checksum formula used to validate a variety of identification numbers, including credit card numbers and IMEI numbers. It was created by IBM scientist Hans Peter Luhn in 1954 and is designed to protect against accidental errors, such as mistyping a single digit.

How it works:

• Start from the rightmost digit (the check digit) and move left.
• Double the value of every second digit.
• If doubling a digit results in a number greater than 9, sum the digits of the product (e.g., 18 becomes 1+8=9).
• Sum all the digits.
• If the total modulo 10 is equal to 0, the number is valid.

Card Issuer Identification Numbers (IIN)

The first few digits of a credit card number, known as the IIN or BIN, identify the issuing network. This tool automatically detects the network based on these standard prefixes: