"old news" (from 2016)
Salesforce Selects Amazon Web Services as Preferred Public Cloud Infrastructure Provider - Salesforce Blog
"Many Salesforce services—including Heroku, Marketing Cloud Social Studio, SalesforceIQ, and the recently announced Salesforce IoT Cloud—run on AWS infrastructure.
Salesforce will expand its use of AWS to core services—including Sales Cloud, Service Cloud, App Cloud, Community Cloud, Analytics Cloud and more—for the company's planned international infrastructure expansion."