Does .NET 4 have a built-in JSON serializer/deserializer?

Does .NET 4 come with any class that serializes/deserializes JSON data?

• I know there are 3rd-party libraries, such as JSON.NET, but I am looking for something built right into .NET.

• I found Data Contracts on MSDN, but it is for WCF, not for Winforms or WPF.

You can use the DataContractJsonSerializer class anywhere you want, it is just a .net class and is not limited to WCF. More info on how to use it here and here.

There's the JavaScriptSerializer class (although you will need to reference the System.Web.Extensions assembly the class works perfectly fine in WinForms/WPF applications). Also even if the DataContractJsonSerializer class was designed for WCF it works fine in client applications.

Use this generic class in order to serialize / deserialize JSON. You can easy serialize complex data structure like this:

Dictionary<string, Tuple<int, int[], bool, string>>

to JSON string and then to save it in application setting or else

public class JsonSerializer
{
    public string Serialize<T>(T aObject) where T : new()
    {
        T serializedObj = new T();
        MemoryStream ms = new MemoryStream(); 
        DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(T));
        ser.WriteObject(ms, aObject);
        byte[] json = ms.ToArray();
        ms.Close();
        return Encoding.UTF8.GetString(json, 0, json.Length);
    }

    public T Deserialize<T>(string aJSON) where T : new()
    {
        T deserializedObj = new T();
        MemoryStream ms = new MemoryStream(Encoding.UTF8.GetBytes(aJSON));
        DataContractJsonSerializer ser = new DataContractJsonSerializer(aJSON.GetType());
        deserializedObj = (T)ser.ReadObject(ms);
        ms.Close();
        return deserializedObj;
    }
}

.NET4 has a built-in JSON Class,such as DataContractJsonSerializer ,but it is very weak,it doesn't support multidimentional array. I suggest you use JSON.Net