One way to go would be to use the (available as of .NET 3.5) DataContractJsonSerializer in the System.Runtime.Serialization.Json Namespace: [
^].
I am not familiar with the System.Web.Helpers facilities, but, I suspect that the Json Class in that library might be useful: [
^].
Mehdi Gholam, here on CodeProject, has excellent code for very fast JSON and BinaryJSON serialize/deserialize: [
^], [
^]. These projects were started in 2011, and Mehdi has been supporting them very generously all along, and updating them, adding new features, and improving performance, frequently.