Circleboom's Servers uses Cloudflare, an immensely popular internet security services provider, to protect its visitors, users, and subscribers. All pages are SSL protect by Cloudflare.
Circleboom uses industry lead payment operator Stripe as its payment processor. Stripe is one of the top credit card processors in the World. (https://www.wired.co.uk/article/stripe-payments-apple-amazon-facebook)
On the upgrade page, we display Stripe's credit card subscription form, and they do the job. All credit card information is stored on Stripe's servers securely. We do not see credit card details during or after the payments.
You can see Stripe’s logo lower-left corner on the upgrade page.