Fraudulent donations are unfortunately a massive problem on the Internet. Fraudulent donations are typically attempted by computer bots (not real humans) that scour the web testing stolen credit cards on payment forms found on the web.
We combat bot traffic primarily with Google Recaptcha. As a GiveForm is filled out, Recaptcha runs in the background and tries to assess if the form is being completed by a human. If Recaptcha believes the user is a bot, GiveForms will display a Recaptcha checkbox to double check that the donor is a human.
While it's not possible to block 100% of fraudulent transactions, this unique implementation of Recaptcha has reduced fraudulent donations by 99.9%.
If a bot attempts to make repeated donations in a short duration, GiveForms automatically bans the donors IP address for a short period.