Validate credit card

Check a payment-card number with the Luhn checksum and mask it for display.

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ToolCredit Card Validator
Input
Output
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Preview

How it works

Separators are removed, digits are walked from the right, alternating digits are doubled with nine subtracted above nine, and the total must divide by ten. Prefix heuristics label common networks while all but the first and last four digits are masked.

  • Thirteen to nineteen digits cover common PAN lengths.
  • Network labels are prefix hints, not issuer confirmation.

Worked example

Valid Visa Card
Validate a Visa test card number (Luhn-valid)
Input
											4111 1111 1111 1111
Output
												Valid card number
Type: Visa
Masked: 4111 **** **** 1111

When to use this

Payment forms, checkout tests, and masked support screens use this check.

Edge cases

  • A Luhn-valid number can still be expired, blocked, or nonexistent.
  • Letters fail before checksum evaluation.
  • Masking changes display only and does not tokenize payment data.

References