Which one to choose between WCF and WEB API ?

 The following points help you to choose between WCF and WEB API:

1. Choose WCF when you want to create a service that should support special scenarios such as one way messaging, message queues, duplex communication etc.
2. Choose WCF when you want to create a service that can use fast transport channels when available, such as TCP, Named Pipes, or maybe even UDP (in WCF 4.5), and you also want to support HTTP when all other transport channels are unavailable.
3. Choose WEB API when you want to create resource-oriented services over HTTP that can use the full features of HTTP (like URIs, request/response headers, caching, versioning, various content formats).
4. Choose WEB API when you want to expose your service to a broad range of clients including browsers, mobiles, iphone and tablets.