Check spelling in TinyMCE

Browser-based spell checking

Assign the browser_spellcheck configuration option the value of true to utilize the browser’s native spell check functionality. Disabling the contextmenu option may be required depending on the right-click or context usability requirement.

tinymce.init({
  selector: 'textarea',  // change this value according to your HTML
  browser_spellcheck: true,
  contextmenu: false
});

When the TinyMCE context menu is enabled, users can still access the browser context menu, including the browser spellchecker, using the Ctrl+Right click shortcut. However if the contextmenu_never_use_native option is enabled, holding the Ctrl key will have no effect.

TinyMCE Spell Checker Pro plugin

Use the Spell Checker Pro plugin for scalable enterprise-grade spell check as-you-type functionality. Spell Checker Pro requires both a client-side plugin to be configured and a server-side component to be installed and configured.