Facebook offers development tools and APIs that enables developers to easily integrate with Facebook. Developers can use Facebook platform to build apps and websites that are more personalized, social, and engaging. Facebook offers developers Open Graph API and Social Plugins that developers can use build different user experiences, including Apps on Facebook, Desktop Apps, Mobile Apps, and Platform-integrated websites. At the end of 2011, more than 7 million apps and websites had been integrated with Facebook. Facebook offers developers an online payment infrastructure that enables developers to receive payments from the users in an easy-to-use and secure environment.
While advertisements remain a key source of revenue for Facebook, the contribution from payments is increasing consistently. Payment revenues increased from nearly 2% in 2009 to 15% in 2011. Ad revenues contributed 85% to the total revenues in 2011.