The feature, called “Purchases on Google,” completes sales using financial information that has already been stored with Google. Participating merchants can still gather information about customers using Google’s buying button.

Facebook also has been testing a similar buying button in ads appearing in its social network. About a dozen retailers are initially using Google’s buying button. Google is hoping to increase the number of merchants before the end of this year.

Micro-blogging service Twitter had also rolled out a new Ads button which is available on the users profile pages on both the iOS and Android client applications. The newly added button is present right next to the 'Edit profile' button, the account switcher and the Settings icon.