It’s completely unclear if that means 0% after the normal CC fees or 0% total. Also it’s only up to $1K, after that you are paying 3.9% (again, unclear if it’s 3.9% total or after CC processing). A lot of companies in this space obscure the true cost of processing until you are already signed up and using it.

It’s almost as bad as the infrastructure monitoring companies that never even ballpark the AWS cost (on top of their SaaS cost) you will end up paying to use their service (aka CloudWatch fees).