using System;

using System.Text.Json;

public class Program

{

    public record GetResponse(

    Information[] Data

);

    public record Information(

    string Key1,

    int? Key2,

    string Key3,

    string Data

    );

    public static void Main()

    {

        var json = @"{

    ""data"": [

        {

            ""key1"": ""Nfddf"",

            ""key2"": 616,

            ""key3"": ""D""

        },

        {

            ""key1"": ""NDwep"",

            ""key2"": 258,

            ""key3"": ""F""

        },

        {

            ""key1"": ""NDIVI"",

            ""key2"": 374,

            ""key3"": ""R""

        }

    ]

}";

        var options = new JsonSerializerOptions

{

    PropertyNameCaseInsensitive = true

};

        var x = JsonSerializer.Deserialize<GetResponse>(json, options);

        var y = JsonSerializer.Serialize(x, options);

        Console.WriteLine(y);

    }

}