I have an app hosted on Google App Engine and I need to have a payment page that uses SSL. GAE only allows you to use SSL on their appspot domain but I want to keep it on my custom domain. Is it appropriate to host my payments page with a different hosting provider that allows SSL on my domain?
GAE only allows you to use SSL on their appspot domain
GAE now (2015) supports SSL for custom domains.
You can do it, but you still need a secure way to deliver payments information to your app. I suppose SDC fill fit for this purpose.