[panamafrank]

PCI compliance i think, also merchants wouldn't touch you with a barge pole if you don't have dedicated hardware... so no aws/gce.

[aroch]

Contemporary PCI compliance does not require dedicated hardware -- You can by PCI Level I compliant on DO, AWS and many other shared-infra providers.

Also, worth noting, since most places are integrating payments through, e.g., Stripe, the requirements on the gateway server are much lower.

[pfg]

You can definitely run PCI compliant infrastructure on services such as AWS. Stripe runs on AWS IIRC. Many (most?) AWS services are PCI compliant and using them won't prevent you from being PCI certified.