This book will be to focus on how we can develop basic enterprise level application architecture with Web API’s. The complete book will be in a way that focuses on less theory and more practical scenarios to understand how RESTful services can be created using an ORM (Object-relational mapping) i.e Entity Framework here. The first chapter in the book is to set up a basic architecture of REST service based application using Asp.net MVC. This chapter explains how to expose pure REST (Representational State Transfer) endpoints of the service that could be consumed by any client which wishes to use REST services. It also explains the implementation of Entity Framework in conjunction with Repository Pattern and Unit of Work also focuses on how to create a generic repository for all the entities that may come up as the application expands, in short it should be quite scalable and extensible. The second chapter in the book talks about loosely coupled architecture. It throws some light on how we can achieve a loosely coupled architecture in Asp.Net WebAPI’s using UnityContainer and Bootstrapper and explaining Dependency injection. The third chapter is about overcoming the flaws of UnityContainer. It explains how we can leverage MEF(Managed Extensibility Framework) to resolve the dependencies at runtime using IOC(Inversion of Control). Unlike other web services, Asp.net WebAPI supports attribute-based routeing techniques.The fourth chapter of the book explains how we can get multiple endpoints of a WebAPI using Attribute Routing and also overcome of the traditional shortcomings of REST based services. Security is always a concern in Enterprise level applications, Chapter 5 of the book explains how one can implement a custom token based authentication technique to make the API’s more secure. Sixth chapter of the book will explain the implementation of a centralised approach to logging and exception handling with the help of Action Filters and Exception filters. It teaches how to implement nLog in conjunction with Filters. Developing an enterprise level infrastructure without Unit tests is worth not developing it. Chapter 7 and 8 teaches how to leverage nUnit to accomplish this task of Unit Testing in WebAPIs. The chapter in detail describes how to write and execute unit tests for services and controllers. Chapter 9 of the series teaches the newly emerging concept of OData. It teaches on how one can request a service with custom needs and requirements, on how one can implement OData support to WebAPIs. Last but not the least is API hosting. In the last section of the book, the 10th chapter describes WebAPI hosting a self-host application.