Google APIs are application programming interfaces developed by Google which allow communication with Google Services and their integration to other services.
PayPal is a American international e-commerce service that enables companies and individuals to send money and to accept payments without revealing any financial details.
The Open Graph protocol enables any web page to become a rich object in a social graph, a open protocol supported by Facebook
Chrome for Android, since version 39 supports the "theme-color" meta tag to allow websites control the background color of the tab's UI header.
Google's hosted library for web fonts. Allows websites to choose and use fonts from a free, wide variety of fonts.