Smart Shopping campaigns were released in AdWords API v201802 to whitelisted advertisers. Today, we’re releasing them to all developers in both the 
AdWords API and 
Google Ads API.
Smart Shopping campaigns combine automation and machine learning to 
maximize your conversion value across networks based on your budget. For end-to-end instructions in creating Smart Shopping campaigns, ad groups, and ads, visit our docs: 
AdWords API guide or 
Google Ads API guide.
For optimal performance, we recommend you have at least 20 conversions over the last 45 days across existing Shopping campaigns before creating a Smart Shopping campaign. 
As always, if you have any questions or concerns, please post them on our 
forum.
 - Thanet Praneenararat, Google Ads API Team
 - Thanet Praneenararat, Google Ads API Team