We utilize Stripe for all payment processing because they have proven for years to be bulletproof. When you upgrade, your payment information doesn't even touch our website, rather it's encrypted and transmitted directly to Stripe. Stripe has been audited by a PCI-certified auditor and is certified to PCI Service Provider Level 1. This is the most stringent level of certification available in the payments industry. For detailed information regarding security you can review the official documentation at https://stripe.com/docs/security/stripe