Credit Card Validator
The Luhn algorithm catches typing mistakes in card numbers, and the first digits reveal the brand. Enter a number to check both instantly in your browser. Nothing is uploaded, so use test numbers only and never a real card.
Use only test numbers such as 4242 4242 4242 4242 when developing checkout forms.
How to use
- Type or paste a card number (spaces are ignored).
- The Luhn result, brand and masked number update live.
- Use test numbers only while building and testing payment forms.
Tips
- This checks the number's format only - a valid Luhn result does not mean the card is real or funded.
- Payment forms should validate again on the server; browser checks can be bypassed.
- Use the well-known test numbers from Stripe or PayPal docs while building.
- Mask stored or displayed card numbers and never log full numbers.
Note: A valid Luhn result only means the number is well formed — it does not mean the card exists or has funds. Never type a real card number into any website tool.
Frequently Asked Questions (FAQ)
How does the validation work?
It runs the Luhn checksum algorithm on the number and detects the card brand from its prefix.
Is my card number sent anywhere?
No. Validation runs only in your browser. Never enter a real card number in any online tool.
What is it good for?
Testing payment forms and checkout validation with test numbers while you are building.
Does a passing check mean the card is real?
No. It only checks that the number format is structurally valid, not that the account exists.