Ajax request from jQuery to Web Api - this is how to do it.

ajax to mvc

  $.ajax({
    url: 'YOUR WEB API URL',
    type: 'POST/PUT/WHATEVER',
    dataType: 'json',
    contentType: 'application/json; charset=utf-8', //IMPORTANT!
    data: JSON.stringify(appId), 
    success: function () { alert('COMPLETED!'); },
    error: function (xhr, message, error) {
    alert(error);
    }
    });