---
title: TinyMCE spellchecker
slug: cms-13/docs/optimizely-spellchecker-for-tinymce
docTags: 
createdAt: 2026-07-30T20:22:07.220Z
---

:::hint{type="info"}
**Version information**
`EPiServer.TinyMCESpellChecker` 3.0.2 works only with `EPiServer.CMS.TinyMce` 3.x.

`EPiServer.CMS.TinyMce` 4.x and above have the spellchecker built into TinyMCE. You do not need to install spellchecker for TinyMCE 4.x. Add the following code in `Startup.cs` to enable the spellchecker:

`services.AddTinyMce().AddTinyMceSpellChecker(); `
:::

The Optimizely spellchecker for TinyMCE adds spell-checking to the rich-text editor in CMS. Content authors see inline spelling suggestions as they type, reducing errors before publishing.

![](https://api.archbee.com/api/optimize/BrbvVORKJ5iIeSMZye5kI/5BNICMnyYMj-n5IyHhqDv-20260722-194646.png)

## Requirements

Confirm that your environment meets the following requirements before installing the spellchecker add-on.

- No additional license fee.
- An Optimizely Content Management System (CMS) 13 or Optimizely Customized Commerce installation.
- See [Apps platform compatibility](docId\:oGp5aaps96qkEIgnCuF_p) for package and version information.
- Installed `EPiServer.CMS.TinyMce` [NuGet](https://nuget.optimizely.com/packages/episerver.cms.tinymce) package.

## Install

Install the spellchecker by registering it in your application startup pipeline.

In the `Startup.cs` file, add the following call to `AddTinyMceSpellChecker`:

```csharp
services.AddMvc();
services.AddAlloy();
services.AddCmsHost()
  .AddCmsHtmlHelpers()
  .AddCmsUI()
  .AddAdmin()
  .AddVisitorGroupsUI()
  .AddTinyMce()
  .AddTinyMceSpellChecker()
  .AddAdminUserRegistration(options => options.Behavior = RegisterAdminUserBehaviors.Enabled |
                                                          RegisterAdminUserBehaviors.LocalRequestsOnly);
```

## Configure

The spellchecker add-on includes predefined language dictionaries. Add dictionaries for additional languages to support your content authors.

The following sections describe how to configure the Optimizely spellchecker for the TinyMCE add-on.

### Default language dictionaries

The following dictionaries are included with the add-on by default:

- Danish (da)
- German (de)
- English (en-US)
- Spanish (es)
- French (fr)
- Italian (it)
- Dutch (nl)
- Norwegian Bokmål (nb-NO)
- Norwegian Nynorsk (nn-NO)
- Polish (pl)
- Portuguese (pt)
- Russian (ru)
- Swedish (sv)

### Add dictionaries

Add dictionaries to the website. Download dictionary file sources, for example, from [Mozilla Language Tools](https://addons.mozilla.org/en-US/firefox/language-tools/). Language packages from these sources are not designed for the spellchecker, but the `.aff` and `.dic` files they contain are compatible.

1. Download the desired language package.
2. Rename the downloaded file to `.zip` and extract the `.aff` and `.dic` files.
3. Create a folder named by language code (for example, `en-GB`) in the website root folder `\EPiServer.TinyMCESpellChecker\SpellChecker\Dictionaries`. This path persists across add-on updates.
4. Paste the extracted `.aff` and `.dic` files into the created folder.

:::hint{type="warning"}
- **Important**
  Enable the language on the website before the dictionary appears in the spellchecker language list.
- The dictionary file name must match the language code of the language branch enabled in Optimizely. For example, if you enabled `en-GB`, name your dictionary files `en-GB.dic` and `en-GB.aff`.
- Check which language variations your dictionaries cover. A dictionary named `en.dic` often covers US English, which in Optimizely is `en-US`. Similarly, `no.dic` often covers `Norwegian Bokmal`, which in Optimizely is `nb-NO`. Most downloadable dictionaries include a README with this information.
- Place only one dictionary in each language folder to avoid conflicts. For example, do not place both `en.dic` and `en-US.dic` in the `en` folder.
:::

### Use spellchecker for specific properties

The spellchecker applies to all `XhtmlString` properties by default. To restrict the spellchecker to specific properties, configure the site as shown in the following example.

The following example enables the spellchecker only for the `MainBody` property on `ProductPage`:

```csharp
const string SpellCheckerPluginName = "spellchecker";
services.Configure<TinyMceConfiguration>(config =>
{
    var defaultSettings = config.Default();

    // Add the plugin but NOT to the default toolbar
    defaultSettings.AddTinyMceSpellCheckerPlugin();

    // Apply spellchecker toolbar only for ProductPage.MainBody
    var defaultToolbar = defaultSettings["toolbar"] as string[] ?? [];
    var toolbarWithSpellChecker = defaultToolbar.Length > 0
        ? defaultToolbar[0] + " " + SpellCheckerPluginName
        : SpellCheckerPluginName;

    config.For<ProductPage>(p => p.MainBody)
        .Toolbar(toolbarWithSpellChecker);
});
```