The Gravatar PHP SDK by Gravatar allows to communicate with the API to access avatar photo data. With the SDK, developers can send HTTP requests to the API by working with the XML-RPC format. The aim is to find out if an image is available using an email address, submit an image, and assign an image to its respective URL.
WHOIS is a protocol, most often used for querying databases that store information about owners of various Internet resources. When WHOIS is combined with WhoAPI it can become a powerful tool. This article explains how to use WHOIS and offers a number of use cases for using WHOIS with the WhoAPI.
The Moodstocks API provides image recognition services that developers can integrate into their mobile and web applications. The image recognition API allows developers to add reference images and define them--a process that in turn can be used when identifying objects in images.