NU

using Newtonsoft.Json;

var jsonString = JsonConvert.SerializeObject(obj);

using System.Text.Json;

//Serialize
var jsonString = JsonSerializer.Serialize(yourObject);

// Deserialize
var obj = JsonSerializer.Deserialize<YourObject>(stringValue);

jsonString = File.ReadAllText(fileName);
weatherForecast = JsonSerializer.Deserialize<WeatherForecast>(jsonString);

var json = new JavaScriptSerializer().Serialize(obj);

string jsonString = JsonSerializer.Serialize(weatherForecast);