No 'Access-Control-Allow-Origin' header is present on the requested resource.

//No 'Access-Control-Allow-Origin' header is present on the requested resource__

Access-Control-Allow-Origin error mostly when you access web api without client like from ajax or javascrip call

Issue can be resolved in following steps.

1) Goto global aspx calss of WebApi

2) After default start method add below mentioned code in step 3

3) protected void Application_BeginRequest(object sender, EventArgs e)
        {
            HttpContext.Current.Response.AddHeader("Access-Control-Allow-Origin", "*");
            if (HttpContext.Current.Request.HttpMethod == "OPTIONS")
            {
                HttpContext.Current.Response.AddHeader("Access-Control-Allow-Methods", "POST, PUT, DELETE");
                HttpContext.Current.Response.AddHeader("Access-Control-Allow-Headers", "Content-Type, Accept");
                HttpContext.Current.Response.AddHeader("Access-Control-Max-Age", "1728000");
                HttpContext.Current.Response.End();
            }
        }


___Stay Happy_____________