We can assure you that payment processing on PicMonkey is always 100% secure. We are as concerned as you are about credit card security!
Https and the Padlock Icon:
All credit card information is sent securely over https, even though the browser bar doesn't show the padlock.
For extra reassurance, we invite you to upgrade on this page https://www.picmonkey.com/#register to get the padlock icon in the browser bar. Another option is to upgrade with PayPal.