HTML editable controls:
<input> disabled by default
<textarea>
Elements with contenteditable attribute set to ‘true’:
<div>
<iframe>
* The dialog mode of WProofreader is not supported with real-time collaboration features or multi-root editor modes of CKEditor 5.
** Integration with Slate.js and Draft won't work properly with IE11.
WProofreader also has a plugin for WordPress 4.x and WordPress 5.x. For more details, check the official repository of WProofreader plugin for WordPress.