How to manually parse a JSON string in net-core 2.0

Yes. You can add Newtonsoft.json package to your .net core project. And to query the dynamic json object, you can use the JObject object provided by the library to parse your json into a dynamic object. Here is the link for the document.

Given your json sample it may look like this

 var resource = JObject.Parse(json);
 foreach (var property in resource.fields.Properties())
 {
   Console.WriteLine("{0} - {1}", property.Name, property.Value);
 }

Json.NET is the go-to library when you are serializing .NET objects. However, when structure of objects is not static, APIs from System.Json namespace will be simpler to use. System.Json can be used in .NET Core 2.0 by installing a package from NuGet like this:

dotnet add package System.Json --version 4.4.0

Here is a nice tutorial on how to use APIs from System.Json namespace: Working with JSON in .NET – a Silverlight example