Bilal,
What makes you think that TinyMCESpellChecker 2.0.0 makes an XHR request to a resource on HTTP?

I created a support ticket 394523 at support episerver com. Follow this ticket if you run into this problem.

Hi Bilal, Please post the answer here once you received the solution for this issue.

Hi Bilal,

Sorry for the slow progress. I've been home sick unfortunately.

Could you try and set it up with this structure instead and see if that helps (So the code is within the initialize method), seems like it's working for me then.:

using EPiServer.Cms.TinyMce.Core;
using EPiServer.Framework;
using EPiServer.Framework.Initialization;
using EPiServer.ServiceLocation;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using System.Web;
using TestGoogleTag.Models.Pages;

namespace TestGoogleTag.SpellChecker
{
    [ModuleDependency(typeof(EPiServer.TinyMCESpellChecker.InitializationModule))]
    public class CustomizedTinyMceSpellCheckerInitialization : IConfigurableModule
    {
        private ServiceConfigurationContext _serviceConfigurationContext;
        private const string SpellCheckerPluginName = "spellchecker";

        public void Initialize(InitializationEngine context)
        {
            _serviceConfigurationContext.Services.Configure<TinyMceConfiguration>(config =>
            {
                var defaultSettings = config.Default();
                var defaultToolbarSettings = defaultSettings["toolbar"] as string[] ?? new string[1];

                config.For<ProductPage>(p => p.MainBody)
                    .Toolbar("spellchecker fullscreen image");

            });
        }

        public void Uninitialize(InitializationEngine context)
        {
        }

        public void ConfigureContainer(ServiceConfigurationContext context)
        {
            _serviceConfigurationContext = context;
        }
    }
}