An Application Programming Interface, or API, defines the classes, methods, functions, and variables that your application will need to call in order to carry out its desired task. In the case of PHP applications that need to communicate with databases, the necessary APIs are usually exposed via PHP extensions. So I designed and developed RestFul API for big-level desktop and mobile applications. Moreover, I integrated a lot of third-party apis. For Example Mandrill, MailChimp, EchoSign, DropBox, Google Drive, PayPal, Recurly, ChargeBee, Stripe, and Braintree all social media & API development as per client requirements.