Credit Card Number Validator
Check whether a card number is a structurally valid number using the Luhn checksum algorithm, and see its likely card network based on the leading digits. Everything runs locally in your browser — the number is never transmitted, stored, or checked against any real account.
How to Use the Credit Card Number Validator
- Type a card number into the field — spaces are added automatically every 4 digits as you type.
- Click "Validate" to run the Luhn checksum algorithm against the number.
- Check the network badge for a guess at the card brand (Visa, Mastercard, Amex, Discover) based on its prefix.
- Review the ✅/❌ result to see if the number passes the checksum.
Why Use This Tool?
What does this tool actually check?
This only checks number FORMAT validity using the Luhn checksum — it never verifies a real account, checks balance, or charges anything. The Luhn algorithm is a simple mathematical checksum built into the numbering scheme of real card numbers, used to catch typos and mis-scans. Passing this check means the number is structurally well-formed; it does not mean the card is active, real, or has any funds. This tool is intended for educational and software-testing use only.
Is my card number stored or transmitted?
No. All validation happens instantly in your browser using JavaScript. The number you type is never sent to a server, logged, or saved by this site in any form.
How is the card network detected?
The network badge is a simple guess based on well-known prefix ranges: Visa numbers start with 4; Mastercard numbers start with 51–55 or 2221–2720; American Express starts with 34 or 37; Discover starts with 6011 or 65. This is a heuristic, not an authoritative lookup.
What is this tool useful for?
Developers commonly use Luhn-valid test numbers (like the well-known 4111 1111 1111 1111 Visa test number) to check that checkout forms handle card input correctly, without needing a real card. This tool helps confirm whether a sample number you're using in testing is Luhn-valid.