Credit Card Validator
Validate credit card numbers using the Luhn algorithm and detect card type.
Credit Card Validator β Luhn Algorithm Checker
Credit Card Validator uses the Luhn algorithm (modulus 10) to validate credit card numbers and automatically detects the card network.
Enter a credit card number in the input field and the tool instantly validates it using the Luhn algorithm (modulus 10 check). The algorithm verifies that the checksum digit matches the rest of the number, catching typos and random digit strings. The tool also identifies the card network (Visa, Mastercard, Amex, Discover, etc.) based on the number's prefix and length. A green indicator shows valid numbers, while red indicates invalid numbers that fail the Luhn check. This validation confirms the number is mathematically correct but doesn't verify the card exists or has funds. All computation runs in your browser.
E-commerce developers test checkout form validation logic by entering various valid and invalid card numbers to ensure proper error handling. Payment processing teams troubleshoot integration issues by verifying that card numbers they receive are at least structurally valid before attempting authorization. Quality assurance testers use this during payment flow testing with test card numbers provided by payment processors. Customer support agents validate card numbers customers provide over the phone to catch transcription errors before processing.
Passing Luhn validation only means the number could theoretically be a real card; it doesn't confirm the card is active, has credit available, or belongs to the customer. All major card networks use Luhn, so this is a good first-pass check before making expensive API calls to payment processors. Test card numbers for development often have predictable patterns like 4111111111111111 for Visa; this tool confirms they're valid for testing. Never use this tool to validate card numbers you found or generated for fraudulent use; this is strictly for development, testing, and legitimate troubleshooting.
All processing happens directly in your browser. Your files never leave your device β no server uploads, no cloud storage, no data retention. The tool works offline once loaded, requires no registration, and is completely free with no usage limits.
Frequently Asked Questions
What is the Luhn algorithm?
The Luhn algorithm (also known as modulus 10) is a checksum formula used to validate identification numbers including credit card numbers.
Is this tool safe to use?
Yes. All validation happens locally in your browser. No data is sent to any server or stored anywhere.
Can this tool process payments?
No. This tool only validates the number format. It cannot check if a card is active, has funds, or process any transaction.
How does card type detection work?
Card networks use specific number ranges (BIN/IIN). For example, Visa cards start with 4, Mastercard with 51-55 or 2221-2720.
Why is my test card number invalid?
The number must pass the Luhn checksum. Many randomly typed numbers will fail. Use known test card numbers from payment processor documentation.