Credit Card Primary Account Number (PAN) Masker & Luhn Validator
Validates credit card numbers using the Luhn algorithm and masks all digits except the last four.
Notice: engineering verification utility. Use test or de-identified data and verify results independently before relying on them.
How it works
Standard: PCI-DSS v4.0 Requirement 3.4 / Luhn Algorithm
Formula: Luhn checksum verification and 16-digit truncation masking
Checks: 13 to 19 digit numeric card string
Calculated locally in browser memory; nothing leaves your browser.
Deterministic local-first client-side execution. Provided as-is without warranty.