Snappy Checkout offers all services over a secure HTTPS connection. When your customers pay via Stripe from your checkout, your customer's credit card information is sent to Stripe over a secure HTTPS connection. When your customers pay via PayPal from your checkout, their credit card information is collected over a secure HTTPS connection on PayPal's website.

You have the choice between hosting your checkout on your own website or at snappycheckout.com. When hosting your own checkout, it is safer (but not required) to display your checkout on a webpage that is HTTPS secured. This means your webpage URL would start with https:// rather than http://.

If you need more information on how to install a SSL certificate to enable a secure HTTP connection, then head over to Stripe's Help Page for SSL. They did an awesome job of explaining that entire process.
Snappy Checkout never stores sensitive credit information entered by your customers.

All sensitive credit card data is securely transmitted, processed, and stored by Stripe and PayPal. Both companies are PCI-compliant — meaning they are routinely audited to ensure they are following the strictest security standards.
Snappy Checkout allows you to protect your account with Google 2-Step Verification. When enabled, you'll need both your password and a code generated on your mobile phone (or other mobile device) in order to log into the Snappy Checkout admin.

It's a small inconvenience that offers a greater level of protection.