JSON Media-Type Formatter

Camel Casing

var json = GlobalConfiguration.Configuration.Formatters.JsonFormatter;
json.SerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver();

Convert all dates to UTC

var json = GlobalConfiguration.Configuration.Formatters.JsonFormatter;
json.SerializerSettings.DateTimeZoneHandling = Newtonsoft.Json.DateTimeZoneHandling.Utc;

Handling Circular Object References

public class Employee
{
    public string Name { get; set; }
    public Department Department { get; set; }
}

public class Department
{
    public string Name { get; set; }
    public Employee Manager { get; set; }
}

public class DepartmentsController : ApiController
{
    public Department Get(int id)
    {
        Department sales = new Department() { Name = "Sales" };
        Employee alice = new Employee() { Name = "Alice", Department = sales };
        sales.Manager = alice;
        return sales;
    }
}

===========================================================================================

var json = GlobalConfiguration.Configuration.Formatters.JsonFormatter;
json.SerializerSettings.PreserveReferencesHandling = 
    Newtonsoft.Json.PreserveReferencesHandling.All;

will produce following result :

{"$id":"1","Name":"Sales","Manager":{"$id":"2","Name":"Alice","Department":{"$ref":"1"}}}

Removing the JSON or XML Formatter

void ConfigureApi(HttpConfiguration config)
{
    // Remove the JSON formatter
    config.Formatters.Remove(config.Formatters.JsonFormatter);

    // or

    // Remove the XML formatter
    config.Formatters.Remove(config.Formatters.XmlFormatter);
}