[throw238513]

MaxMind's minFraud[0] was the most popular last time I checked. You give them the credit card info, the IP of the user, their email etc[1] and $0.005 (per credit card transaction you want them to check) and they tell you the probability that it's fraud.

At my company we use Stripe as our payment processor, which has their own fraud detection called Radar. But still, a bit under .1% of our transactions are fraudulent.

Credit card fraud is honestly a great business, even if they know you're doing it, the police wont do anything, and the merchant has to cover the cost and pay $15 for the privilege of being defrauded.

[0] https://www.maxmind.com/en/minfraud-services

[1] https://minfraud.readthedocs.io/en/latest/

Sorta related, turns out there are anti-fraud services for fraudsters https://krebsonsecurity.com/2013/11/anti-fraud-service-for-f...

[column]

isn't this the kind of service that will flag a legitimate user behind a VPN as a potential threat because his ip has been used in multiple transactions? Should a user switch off his VPN to do shopping?

[GuB-42]

If that VPN IP range is known to be used by fraudsters then yes, for good reasons. And if your VPN is affordable and "privacy oriented" there is a very good chance that a bunch of crooks are going to use it.

Professional VPNs are probably fine.