Json.NET

JSON is a light-weight, language independent, data interchange format. In today's Internet it is a widely used format for storing and transferring data between applications and various programming languages.

Json.NET is a C# tool that can both convert to and from the JSON format, writing and reading data as needed.

The library can handle both normal .NET objects-to-JSON and vice versa, along with LINQ-to-JSON and vice versa, and XML-to-JSON and vice versa.

On top of this, Json.NET is also considerably faster than .NET's built-in JSON serializers and produces properly formatted JSON data, much more easier to read than the mangled text that the built-in serializers normally output.

Json.NET is also available via NuGet.

What is new in this release:

• New features:
• DiscriminatedUnionConverter performance improvements
• Added JsonRequiredAttribute
• Added JsonSerializerSettings.ReferenceResolverProvider property
• Added DefaultContractResolver.ResolveDictionaryKey
• Added JsonDictionaryContract.DictionaryKeyResolver
• Added support for reading GUID strings as bytes in JsonTextReader
• Added EqualityComparer to JsonSerializer
• Changes:
• Changed reading GUIDs as bytes to only support 00000000-0000-0000-0000-000000000000 format
• Renamed aspnetcore50 target to dnxcore50
• Marked JsonSchema as obsolete
• Marked DefaultContractResolver(bool) as obsolete
• Marked JsonSerializerSettings.ReferenceResolver as obsolete
• Marked JsonDictionaryContract.PropertyNameResolver as obsolete
• Fixes:
• Fixed deserializing empty strings in Hashtables
• Fixed incorrect JTokenReader.Path in certain situations
• Fixed error when serializing certain objects in medium trust
• Fixed deserializing large nullable UInt64 values
• Fixed writing large UInt64 JValues
• Fixed converting unmatched namespace prefixes in JSON to XML
• Fixed IsoDateTimeConverter on DateTime properties with DateTimeFormatHandling.DateTimeOffset
• Fixed preserving object references with read only properties
• Fixed error when deserializing large JSON integers to XML
• Fixed serializing extension data properties with no setter
• Fixed serializing discriminated unions with type name or reference tracking enabled
• Fixed DataTableConverter not using JsonSerializer settings
• Fixed resolving properties from nested interfaces
• Fixed deserializing classes derived from ConcurrentDictionary
• Fixed passing default values to constructors
• Fixed serializing root references from JsonConverters
• Fixed empty strings coerced to null not erroring with Required.Always
• Fixed invalid Required.Always error with constructor property name casing
• Fixed empty string coerce check with Required.Always and constructor

What is new in version 6.0 Release 8:

• New feature:
• Added AttributeProvider to JsonProperty
• Fixed:
• Serializing and deserializing const fields
• Using MetadataTypeAttribute with proxy classes
• Bad error message when deserializing unsupported collections

What is new in version 6.0 Release 4:

• New feature:
• Added Merge to LINQ to JSON
• Added JValue.CreateNull and JValue.CreateUndefined
• Added Windows Phone 8.1 support to .NET 4.0 portable assembly
• Added OverrideCreator to JsonObjectContract
• Added support for overriding the creation of interfaces and abstract types
• Added support for reading UUID BSON binary values as a Guid
• Added MetadataPropertyHandling.Ignore
• Improved performance of KeyValuePairConverter
• Improved performance when serializing large XML documents
• Changes:
• Limited integer parsing size to JavaScript integer size
• Validated that numbers don't end with an invalid character
• Fixes:
• Fixed JToken.ReadFrom creating a string value for a comment
• Fixed relying on Dictionary order when calling parameterized constructors
• Fixed writing new lines to use TextWriter.WriteLine
• Fixed deserializing non-generic IReadOnlyCollection<T> implementations
• Fixed sending HTTP requests when resolving DTD urls in XmlNodeConverter
• Fixed populating ignored properties with DefaultValueHandling.IgnoreAndPopulate
• Fixed not throwing JsonReaderException when parsing some invalid numbers
• Fixed JsonConvert.PopulateObject not setting JsonReader settings

What is new in version 6.0 Release 2:

• New feature:
• Added support for Windows Phone 8.1.

What is new in version 6.0 Release 1:

• New feature:
• Added support for JSONPath
• Added support for serializing F# discriminated unions
• Added support for deserializing nested DataTables and arrays in DataTables
• Added support for reading multiple pieces of JSON with a JsonReader
• Added AllowIntegerValues setting to StringEnumConverter
• Added Decimal and DateTimeOffset constructors to JValue
• Added support for reading JSON single line comments
• Improved number parsing error messages
• Change:
• Assembly version to 6.0.0.0
• .NET 4 Portable build targets MonoTouch and MonoDroid in NuGet package
• .NET 4 Portable build targets WP8 and SL5 instead of WP7 and SL4
• Removed:
• DefaultMemberSearchFlags on DefaultContractResolver is obsolete
• SerializeObjectAsync, DeserializeObjectAsync, PopulateObjectAsync on JsonConvert are obsolete
• Fixed:
• JObject ICustomTypeDescriptor properties returning incorrect value
• Error when casting dynamic base64 string to byte array
• EntityKeyMemberConverter not using property name resolve
• Serializing JValues with readonly JsonConverters
• Formatting override on SerializeObject methods
• Error when wrapping an exception in a JsonConverter
• Using extension data with a non-default constructor
• Uri serialization roundtripping with Uri.OriginalString

What is new in version 5.0 Release 7:

• New feature:
• Added support for Immutable Collections
• Added WriteData and ReadData settings to DataExtensionAttribute
• Added reference and type name handling support to extension data
• Added default value and required support to constructor deserialization
• Changes:
• Extension data is now written when serializing
• Fixes:
• Added missing casts to JToken
• Fixed parsing large floating point numbers
• Fixed not parsing some ISO date timezones
• Fixed schema validation of integer value when type was number
• Fixed writing of IConvertible values when TypeCode returned was Object

What is new in version 5.0 Release 6:

• New feature:
• Added serialized/deserialized JSON to verbose tracing.
• Added support for using type name handling with ISerializable content.
• Fixed:
• Not using default serializer settings with primitive values and JToken.ToObject.
• Error writing BigIntegers with JsonWriter.WriteToken.
• Serializing and deserializing flag enums with EnumMember attribute.
• Error deserializing interfaces with a valid type converter.
• Error deserializing ISerializable objects that also implement IConvertible.

What is new in version 5.0 Release 5:

• New feature:
• Added global default serialization settings with JsonConvert.DefaultSettings
• Added extension data support with JsonExtensionDataAttribute
• Added NullValueHandling and DefaultValueHandling support to serializing dynamic types
• Changes:
• Some explicit interface methods on JArray to public to support use with ImpromtuInterface
• Fixed:
• Deserializing non-ISO formatted date dictionary keys
• Values not being set when deserializing with DefaultValueHandling.IgnoreAndPopulate
• Deserializing with type named handling and assemblies loaded with Assembly.LoadFrom
• Deserializing Regexes when using StringEnumConverter
• Serializing and deserializing typed DataSets

What is new in version 5.0 Release 4:

• New feature - Added JsonWriter.SetWriteState to support inheritance from JsonWriter implementations
• Change - Changed .NET 4.5 portable library and WinRT library to use compiled expressions reflection

What is new in version 5.0 Release 3:

• Fixed error serializing non-generic types that implement IEnumerable<T>.