Credit Card Validator
Validate credit card numbers using the Luhn algorithm. Detect Visa, Mastercard, Amex, and more card types instantly.
About Credit Card Validator
The Credit Card Validator is a developer-focused tool that checks whether a credit card number is structurally valid and identifies the issuing card network. It is designed for testing, debugging, and learning about payment card number formats.
How validation works
Every credit card number includes a built-in checksum verified by the Luhn algorithm (also called the mod-10 algorithm). This tool applies that algorithm in real time as you type, giving you instant feedback on whether the number is valid. It also detects the card type by matching the number's leading digits against known Issuer Identification Number (IIN) ranges for Visa, Mastercard, American Express, Discover, Diners Club, and JCB.
Test card number generator
Building a payment integration and need sample numbers? Use the built-in generator to create random, Luhn-valid test card numbers for any supported network. These numbers follow the correct prefix and length rules for each card type and are safe to use in sandbox environments.
Important disclaimer
This tool performs mathematical validation only. It does not verify whether a card is active, has available credit, or is associated with any real account. Never enter a real credit card number into any tool that is not a trusted, PCI-compliant payment processor. The test numbers generated by this tool are intended solely for software development and testing purposes.
Great for learning about the Luhn algorithm, building a checkout flow, or debugging a payment integration.
Frequently Asked Questions
What is the Luhn algorithm?
The Luhn algorithm is a checksum formula used to validate identification numbers such as credit card numbers. It works by doubling every second digit from right to left, subtracting 9 from any result over 9, and checking whether the total is divisible by 10. A valid number passes this test.
Can this tool process real payments?
No. This tool only checks whether a card number has valid formatting and passes the Luhn checksum. It does not contact any bank, payment processor, or card network. It cannot verify whether a card is active, has funds, or belongs to any person.
What are test card numbers?
Test card numbers are syntactically valid numbers that pass the Luhn check but are reserved for development and testing. Payment processors like Stripe and PayPal publish these numbers so developers can test checkout flows without using real cards.
How does card type detection work?
Each card network uses specific number prefixes called IINs (Issuer Identification Numbers). For example, Visa cards start with 4, Mastercard with 51-55 or 2221-2720, and American Express with 34 or 37. This tool matches the entered number against known prefix ranges to identify the card type.