Web API Kit is a set of tools to reduce the code you need to write for the Unity WWW/UnityWebRequest classes, UniWeb, BestHTTP, UnityHTTP, and other popular HTTP providers.
A fully featured HTTP call that supports authentication, timeouts, cancellation, conversion of returned JSON or XML data into a usable C# class would easily be over 200 lines of code. With WAK, all of these features and more are done for you, reducing the code you have to write to 10 lines with the help of C# Attributes.