using System;

using System.Collections.Generic;

using System.Text.Json;

​

/*

​

{

  "Top": {

    "de-DE": "Oben"

  },

  "Taxi": null

}

​

*/

public class Program

{

    const string json = "{\r  \"Top\":{\r    \"de-DE\":\"Oben\"\r  },\r  \"Taxi\":null\r}";

    public static void Main()

    {

        var localizationData = JsonSerializer.Deserialize<LocalizationData>(json);

        Console.WriteLine( "Foo in de-DE: {0}", localizationData.Localize( "Foo", "de-DE" ) );

        Console.WriteLine( "Top in de-DE: {0}", localizationData.Localize( "Top", "de-DE" ) );

        Console.WriteLine( "Taxi in de-DE: {0}", localizationData.Localize( "Taxi", "de-DE" ) );

    }

}

​

class LocalizationData : Dictionary<string,Dictionary<string,string>>

{

    public string Localize( string value, string cultureName)

    {

        if ( !this.TryGetValue( value, out var localization ) )

            return value;

        if ( localization == null )

            return value;

        if ( !localization.TryGetValue( cultureName, out var localizedValue ) )

            return value;

        return localizedValue;

    }

}

​