var formData = new FormData();
var splitedKeywords = $('#keywords').val().split(',');
formData.append('Keywords', JSON.stringify(splitedKeywords));

"\"کلمه اول\",\"کلمه دوم\""

var formData = new FormData();
var splitedKeywords = $('#keywords').val().split(',');
for (var counter = 0; counter < splitedKeywords.length; counter++) {
    formData.append('Keywords', JSON.stringify(splitedKeywords[counter]));
}

dotnet --list-sdks
dotnet new globaljson --sdk-version 2.2.106

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.Scan(scan => scan.FromAssemblyOf<IMessagesService>()
                                  .AddClasses()
                                  .AsMatchingInterface() // Registers all <`IClassName`, `ClassName`>
                                  .WithTransientLifetime()
               );