When you receive a credit card payment via Stripe, Snappy Checkout will run a series of tests to check if the payment was possibly made with a stolen credit card. When a possible fraudulent payment is detected, you will be notified right away via email so you can take the appropriate action. Also, the next time you log into the Snappy Checkout admin, you'll see a red banner across the top of the admin to alert you of the possible fraudulent payment.

All possible fraudulent payments are shown in the Events --> Fraudulent Payments section of the Snappy Checkout admin. From there, you can see why payments were flagged as potentially fraudulent. You can also refund payments if necessary or mark payments as valid payments so they are no longer flagged as potentially fraudulent.

PayPal has their own fraud-prevention program. PayPal will contact you immediately if a payment is found to be possibly fraudulent.