Card Testing for Merchant Services: A Detection and Prevention Guide
Card testing is a fraud attack that floods merchant accounts with low-value authorizations to validate stolen card numbers. Learn the signs and how to stop it.
Choose from any of our gift cards to give to your loved ones
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Redeem your gift cards at any of our Merchants
Merchant Card Verification Test: What It Checks and How to Run One
Onyx Gift Cards is a Grenadian company designed to introduce, market and manage gift cards systems in Grenada for retailers and corporations. We are enthusiastic about the effect and influence we will have on the local market. We intend to expand our systems regionally with a range of product offerings and services.
Gift cards are the preferred way of giving and receiving gifts. They carry a monetary value that can be redeemed for gifts at your favorite store.
Onyx GiftCards are “Open Gift Cards” which means that they can be redeemed at multiple merchant locations. They are standard credit card size, can fit into the average wallet and made of PVC plastic. Onyx GiftCards are Barcoded for security and safety for the consumer and bear a disclaimer at the back.
Onyx Giftcards can be bought with a branded Card backer which is black in colour and is designed to fit the card. There is an area to write a brief message to the recipient as well.
If you accept card payments, your top priority is a fraud prevention service that detects card testing in real time. Look for rate limiting, velocity checks, and machine learning that flags small trial transactions. The right tool blocks attacks without adding friction for real customers. Compare providers on detection speed, false positive rates, and support for your payment stack.
Card testing is a fraud technique where criminals use stolen card numbers to make small purchases. They want to see which cards are still active. If a transaction succeeds, the card is valid and can be used for larger fraud. Common targets include online donations, digital goods, and subscription sign-ups. These attacks can flood your payment gateway with thousands of low-value attempts in minutes.
Card testing hurts your business in several ways. You pay interchange and gateway fees on every attempt, even declined ones. You get chargebacks when cardholders dispute the charges. High decline rates can raise your processing costs or lead to account termination. Card networks may fine you for excessive fraud. A single attack can cost thousands of dollars and damage your reputation.
When you buy fraud protection, evaluate these features:
Use these ranges as a starting point, then tune to your business:
A determined attacker can send thousands of attempts per minute. Without protection, you may see fees and chargebacks within hours.
3D Secure adds a verification step that stops many card testing attempts, but it can reduce conversion. Use it selectively for high-risk transactions.
CAPTCHA helps on forms, but it does not protect direct API calls to your payment gateway. You need server-side fraud controls.
Look for a service with no minimum monthly fee, real-time card testing detection, and easy integration with your ecommerce platform. Read independent reviews and ask for a demo.