How to add and get Header values in WebApi

On the Web API side, simply use Request object instead of creating new HttpRequestMessage

     var re = Request;
    var headers = re.Headers;

    if (headers.Contains("Custom"))
    {
        string token = headers.GetValues("Custom").First();
    }

    return null;

Output -

Suppose we have a API Controller ProductsController : ApiController

There is a Get function which returns some value and expects some input header (for eg. UserName & Password)

[HttpGet]
public IHttpActionResult GetProduct(int id)
{
    System.Net.Http.Headers.HttpRequestHeaders headers = this.Request.Headers;
    string token = string.Empty;
    string pwd = string.Empty;
    if (headers.Contains("username"))
    {
        token = headers.GetValues("username").First();
    }
    if (headers.Contains("password"))
    {
        pwd = headers.GetValues("password").First();
    }
    //code to authenticate and return some thing
    if (!Authenticated(token, pwd)
        return Unauthorized();
    var product = products.FirstOrDefault((p) => p.Id == id);
    if (product == null)
    {
        return NotFound();
    }
    return Ok(product);
}

Now we can send the request from page using JQuery:

$.ajax({
    url: 'api/products/10',
    type: 'GET',
    headers: { 'username': 'test','password':'123' },
    success: function (data) {
        alert(data);
    },
    failure: function (result) {
        alert('Error: ' + result);
    }
});

Hope this helps someone ...