How do I return clean JSON from a WCF Service?

This is accomplished in web.config for your webservice. Set the bindingBehavior to <webHttp> and you will see the clean JSON. The extra "[d]" is set by the default behavior which you need to overwrite.

See in addition this blogpost: http://blog.clauskonrad.net/2010/11/how-to-expose-json-endpoint-from-wcf.html

If you want nice json without hardcoding attributes into your service classes,

use <webHttp defaultOutgoingResponseFormat="Json"/> in your behavior config

Change the return type of your GetResults to be List<Person>.
Eliminate the code that you use to serialize the List to a json string - WCF does this for you automatically.

Using your definition for the Person class, this code works for me:

public List<Person> GetPlayers()
{
    List<Person> players = new List<Person>();
    players.Add(new  Person { FirstName="Peyton", LastName="Manning", Age=35 } );
    players.Add(new  Person { FirstName="Drew", LastName="Brees", Age=31 } );
    players.Add(new  Person { FirstName="Brett", LastName="Favre", Age=58 } );

    return players;
}

results:

[{"Age":35,"FirstName":"Peyton","LastName":"Manning"},  
 {"Age":31,"FirstName":"Drew","LastName":"Brees"},  
 {"Age":58,"FirstName":"Brett","LastName":"Favre"}]

(All on one line)

I also used this attribute on the method:

[WebInvoke(Method = "GET",
           RequestFormat = WebMessageFormat.Json,
           ResponseFormat = WebMessageFormat.Json,
           UriTemplate = "players")]

WebInvoke with Method= "GET" is the same as WebGet, but since some of my methods are POST, I use all WebInvoke for consistency.

The UriTemplate sets the URL at which the method is available. So I can do a GET on http://myserver/myvdir/JsonService.svc/players and it just works.

Also check out IIRF or another URL rewriter to get rid of the .svc in the URI.