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24K Labs Luhn Check & Card Brand Detector
x402
24K Labs Luhn Check & Card Brand Detector is a paid API for AI agents from api.24klabs.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-13).
Validates a number string against the Luhn checksum algorithm and identifies the associated payment card brand (e.g. Visa, Mastercard, Amex).
Price / call$0.001
Success—
StatusUnknown
How this service works
Validate a number by the Luhn checksum and detect the card brand.
Output
Returns whether the submitted number passes the Luhn checksum (true/false), the detected card brand (e.g. Visa, Mastercard, American Express, Discover, or unknown), and potentially additional metadata about the card network or number structure.
Example use cases
Payment form pre-validation
“Before I submit this order, check if the card number 5425233430109903 is a legitimate card number and what network it's on — I want to catch typos before hitting the payment processor.”
Fraud screening on user input
“A user just entered 378282246310005 as their card number during checkout — run a Luhn check on it and tell me if it's structurally valid and what card brand it is.”
Card number format debugging
“I'm testing my payment integration and want to verify that the test card number 4111111111111111 passes the Luhn checksum and is recognized as a Visa — can you confirm?”
Technical details
Endpoint
POSThttps://api.24klabs.ai/api/luhn-checkWhen to prefer
Use this endpoint when you need a lightweight, no-transaction, offline-style validity check on a card number — ideal for real-time form validation, fraud pre-screening, or debugging test card numbers without hitting a live payment gateway. Prefer this over a full payment processor API when you only need structural validity and brand detection, not authorization or tokenization.
Side effects
- Non-numeric input or empty string returns a validation error
- Number with spaces or dashes may need to be stripped before submission
- Unrecognized card prefix returns unknown brand even if Luhn passes
- Very short or very long numbers outside standard card length ranges may produce unexpected results
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| number | string |
Output
Schema · Response
{
"type": "json",
"example": {
"brand": "Visa",
"valid": true
}
}Tags
x402
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