Json.NET

http://james.newtonking.com/projects/json-net.aspx
http://www.codeplex.com/json/
https://github.com/JamesNK/Newtonsoft.Json


Description:

Json.NET is a popular high-performance JSON framework for .NET

-Flexible JSON serializer for converting between .NET objects and JSON
-LINQ to JSON for manually reading and writing JSON
-High performance, faster than .NET's built-in JSON serializers
-Write indented, easy to read JSON
-Convert JSON to and from XML
-Supports .NET 2, .NET 3.5, .NET 4, .NET 4.5, Silverlight, Windows Phone and Windows 8 Store


Documentation:

http://james.newtonking.com/projects/json/help/


Versions:

Json.NET has different libraries for the various .NET Framework versions.

-Net45:
  .NET latest (4.5)

-Net40:
  .NET 4.0

-Net35:
  .NET 3.5

-Net20:
  .NET 2.0

-WinRT:
  Windows 8 Store

-Portable45:
  .NET 4.5, Windows Phone 8, Windows 8 Store

-Portable40:
  .NET 4.0, Windows Phone 7, Windows 8 Store, Silverlight 4


Notes:

Microsoft stopped support for the Compact Framework in Visual Studio 2010.
For a Compact Framework 3.5 build download Json.NET 3.5.

For a Silverlight 3.0 build download Json.NET 3.5.