How to Accept Foreign Credit Cards?

Hi!

We are an American based store and we recently had someone try and purchase an item with a Swedish credit card and the site would not allow them to pay with that card, so I'm trying to figure out how to allow European (and hopefully even world wide?) credit cards to be a payment option.

Are there any guides or info on how to do this?

Thank you for your time!

The site is https://www.allproclassics.com/ if you need to know for any reason.

That depends on your payment processor. I use Stripe and they accept foreign credit cards fine.

We are using Authorize.net

You'd need to contact Authorize.net and see if you need to enable something specific in your account to accept foreign credit cards, and if you don't need to, why that particular card was denied. It's unlikely to have anything to do with OpenCart, at least that I've heard of.