Thank you for contacting Visa Checkout Developer Support.
There are a few card numbers available for testing Visa Checkout integrations.
Visa 4111 1111 1111 1111 MC 5555 5555 5555 4444 AmEx 3782 8224 6310 005 Disc 6011 1111 1111 1117
Remember, Visa Checkout is not a stand-alone payment gateway. For a website to use Visa Checkout successfully, it would already have to have a functional standard checkout payment gateway established through a Merchant Service Provider (MSP). Any responses regarding transaction failure would be provided through that MSP account, not from Visa Checkout.
If you have other questions about Visa Checkout, please submit the inquiry to email@example.com.