An API stand for Application Programming interface which is a set of programming instructions and standards that are used for accessing a Web based software application or Web based tool. In IT sector any company releases its API to the public so that other software developers can design products that are powered by its service. All the operating environments likes MS Windows provide an API so that programmers can write applications consistent with the operating environment. Today all the APIs are also specified by websites for example Amazon or eBay APIs allow developers to use the existing retail infrastructure to create specialized web stores. We also know that all the software developers also use Web APIs to create software solutions for end-users.