All of League Engine's payments are handled through Stripe, which processes billions of dollars annually. Lots of big, recognizable companies (such as Lyft and Shopify) use Stripe for their transactions as well. The way it works is as follows: (1) Players enter their credit card information to pay the league fee right on the website, (2) That information is immediately sent to Stripe without even touching League Engine's servers, (3) Stripe verifies that information and sends back a token (i.e. a unique code), which League Engine can then use to charge that credit card. As a result of the token system, League Engine never sees any actual credit card information; just the code from Stripe, so it is very secure.