Is there any package available of WebApi for .Net framework 3.5? I'm specifically looking forward to use HttpClient component of WebApi.
Is there any alternatives that work on .Net 3.5?
A very mature and very robust library that you can use for HTTP Requests is RestSharp. It has support for OAuth, pluggable serialization, and other HTTP concerns. It supports NET 3.5+, Silverlight 4, Windows Phone 7, Mono, MonoTouch.
It's open source and available via github. Here is a blog post about consuming WebAPI services with RestSharp. Check it out