System.Xml.XPath.XDocument by: Microsoft

Provides extension methods that add System.Xml.XPath support to the System.Xml.XDocument package. Commonly Used Types: System.Xml.XPath.Extensions System.Xml.XPath.XDocumentExtensions

System.Xml.XPath.XmlDocument by: Microsoft

Provides extension methods that add System.Xml.XPath support to the System.Xml.XmlDocument package. Commonly Used Types: System.Xml.XPath.XmlDocumentExtensions

Utf8Json by: neuecc

Definitely Fastest and Zero Allocation JSON Serializer for C#(NET, .NET Core, Unity, Xamarin).