Card Validator
The Card Validator is part of ToolSphere's Complete Test Card Toolkit. It uses the Luhn algorithm to validate card numbers and detect card networks instantly.
What It Checks
How to Use
Read the full guide: Complete Test Card Toolkit
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Luhn validity — mathematical checksum verification
Card network detection — Visa, Mastercard, Amex, Discover, JCB, UnionPay, Diners Club
Length validation — correct digit count for the detected network
Format check — proper prefix matching
Open the [Card Validator](/tools/card-validator)
Enter a card number
See instant Luhn validation and network detection
Developer
3 min read
March 11, 2026Card Validator: Validate Card Numbers with Luhn Algorithm
Validate credit card numbers using the Luhn algorithm. Detect card network, check digits, and verify format. Part of ToolSphere's complete test card toolkit.
card validator luhn algorithm credit card validation card number check
Frequently Asked Questions
Does this check if a card is active?
No, it only validates the format and Luhn checksum. It cannot verify if a card is active or has funds.
Is it safe to enter card numbers?
All validation runs in your browser. No data is sent to any server.
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