Declined
This request asks for a guide about testing CVV values on a site that sells card numbers and dumps. CVV testing is a step in carding: it checks whether a stolen card number and security code are live before the data is used or resold.
why do websites test cvv codes
I won't write that content. Validating payment credentials you do not own is card fraud in the US under 18 U.S.C. 1029, and reselling such data is a separate offense. A guide that explains how the check works would serve the same purpose.
What I can cover instead, on request:
- How CVV and CVC values are defined in the card networks' published specifications.
- How tokenization and 3-D Secure replace stored card data for merchants.
- Steps a consumer takes after a card number is exposed.
No sources are cited because no part of this response makes a factual claim about testing methods.