How To Spell Check Multiple Languages In Firefox?

Being able to speak multiple languages doesn’t mean you are able to write perfectly well in those languages. There are times where misspelled words go unnoticed and the article was published with the error. If you are like me, you will definitely enjoy the spell checking feature in Firefox.

Firefox‘s built-in spell checking feature has been available since Firefox 2. It even has support for multiple languages, which are very useful if your native language is not English.

Simpler Than You Could Imagine

If you have looked around on the Mozilla add-ons site, you might found the page where language packs and dictionaries can be downloaded. At the time of writing this post, 105 dictionaries are available for 86 languages. These packs are actually extensions and you can install them like any other Firefox extension. They will be listed in the “Tools -> Add-ons Manager” menu or by pressing the “Ctrl+Shift+A” hotkey. You can install as many dictionaries as you wish, without limitations.

Add-ons Manager in Firefox 4

I use the English (United States) and the Hungarian dictionaries. Both of them suit my expectations. Apart from the dictionaries for certain commercial spell checker components, these open source dictionaries are maintained continuously and new words are added regularly.

Where Can I Find It?

Right click in the text area where you just typed in the text and find the “Check Spelling” item and the Languages dropdown in the context menu.

The built-in spell checker

The Check Spelling command is activated by default. When you click it, the tick will disappear and the spell checking feature will be disabled. The Languages dropdown will also disappear.

In the Languages dropdown, you can only see those languages that you have installed. If you need a new dictionary, you have an easy job: Just click “Add Dictionaries…“, and it will bring you to the Mozilla Dictionaries & Language Packs page.

How It Works

The spell checking feature works on any web form. It may be the editor of your blog tool or your content management system, the new topic/reply page in a forum, a comment field, or even a contact form on a web page.

Similar to the word processors, an unmatched word is underlined with a red wavy line. When you right click on such a word, you will find suggestions in the pop-up menu, or you can add the word to the dictionary.


Firefox cannot detect automatically the language of your entered text, you have to select it manually in the “Languages” dropdown. Firefox will then perform the spell checking of the text using that dictionary.

Extend It

When you check the Mozilla Add-ons site, you will find a couple of relevant extensions.

Dictionary Switcher

While this is just a small add-on, it is definitely a useful one.. Dictionary Switcher fetches the language from the source code of the page where the web form is available. Another method – the more interesting one – is trying to detect the language of the text you are typing in and switching to that dictionary accordingly.

Dictionary Switcher for Firefox

You can access it from the status bar (now add-on bar since Firefox 4). A dictionary can be selected from the context menu.

When I select the Remember dictionary for current site item in the context menu, it really did not forget the manually set dictionary displayed in bold style.

Quick Locale Switcher

This add-on is more than a simple spell checking dictionary switcher. Quick Locale Switcher cannot detect the language of the entered text, but can automatically set the dictionary for a manually chosen language on a web site you visited.

Quick Locale Switcher extension for Firefox

It also skulks in the add-on bar, perhaps you may access it easier and faster from the Tools menu. The appropriate flags are assigned to the listed languages, still you have to separately download the dictionaries.


Some web based WYSIWYG editors, having their own spell check feature, present a problem, because they may disable Firefox’s right click menu, in addition to this, they may not have a dictionary for your language.

I hope the extensions development will move towards remembering the languages of certain pages. It would be a giant step for the international communities providing international subforums for their members.

In the era of web publishing, the grammatical correctness is not only a human expectation. Due to the sophisticated algorithms of the search engines, it may affect the position of your site in the results list as well.


  1. thanks for your nice entry. i can’t understand how i can life without such extensions.
    now life should be a little bit easier :-D

  2. Nice article.  Is there anyway to have multiple custom dictionaries at once (such as a medical and legal dictionary)?  
    Or is possible to update many users’ custom dictionary with the values of a centrally controlled custom dictionary (such that new medical terms can be added/shared to all users of an internal network)?
    Thanks for any advice/pointers.

    1. Probably not. It should only be able to make use of one dictionary at one time.

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