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Changing the Language of Firefox Directly From the Browser

Language Settings

In Firefox there are two main user facing settings related to languages:

• Web content: when you visit a web page, the browser will communicate to the server which languages you’d like to see content in. Technically, this is done by sending an Accept-Language HTTP header, which contains a list of locale codes in the user’s preferred order.
• User interface: the language in which you want to see the browser (menus, preferences, etc.).

The difference between the two is not as intuitive as it might seem. A lot of users change the web content settings, and expect the user interface to change.

The Legacy Chaos

While the preferences for web content have been exposed in Firefox since its first versions, changing the language used for the user interface has always been challenging. Here’s the painful journey users had to face until a few months ago:

• First of all, you need to be aware that there are other languages available. There are no preferences exposing this information, and documentation is spread across different websites.
• You need to find and install a language pack – a special type of add-on – from addons.mozilla.org.
• If the language used in the operating system is different from the one you’re trying to install in Firefox, you need to create a new preference in about:config, and set it to the correct locale code. Before Firefox 59 and intl.locale.requested, you would need to manually set the general.useragent.locale pref in any case, not just when there’s a discrepancy.

The alternative is to install a build of Firefox already localized in your preferred language. But, once again, they’re not so easy to find. Imagine you work in a corporate environment that provides you with an operating system in English (en-US). You search the Web for “Firefox download”, and automatically end up on this download page, which doesn’t provide information on the language you’re about to download. You need to pay a lot of attention and notice the link to other languages.

If you already installed Firefox in the wrong language, you need to uninstall it, find the installer in the correct language, and reinstall it. As part of the uninstall process on Windows, we ask users to volunteer for a quick survey to explain why they’re uninstalling the browser, and the amount of them saying something along the line of “wrong language” or “need to reinstall in the right language” is staggering, especially considering this is an optional comment within an optional survey. It’s a clear signal, if one was ever needed, that things need to improve.

Everything Changes with Firefox 65

Fast forward to Firefox 65:

We introduced a new Language section. Directly from the General pane it’s now possible to switch between languages already available in Firefox, removing the need for manually setting preferences in about:config. What if the language is not available? Then you can simply Search for more languages… from the dropdown menu.

Add your preferred language to the list (French in this case).

And restart the browser to have the interface localized in French. Notice how the message is displayed in both languages, to provide users with another hint to the user that they selected the right language.

If you’re curious, you can see a diagram of the complete user interaction here.

A lot happens under the hood for this brief interaction:

• When the user asks for more languages, Firefox connects to addons.mozilla.org via API to retrieve the list of languages available for the version in use.
• When the user adds the language, Firefox downloads and installs the language pack for the associated locale code.
• In order to improve the user experience, if available it also downloads dictionaries associated with the requested language.
• When the browser is restarted, the new locale code is set as first in the intl.locale.requested preference.

This feature is enabled by default in Beta and Release versions of Firefox. Language packs are not reliable on Nightly, given that strings change frequently, and a language still considered compatible but incomplete could lead to a completely broken browser (condition known as “yellow screen of death“, where the XUL breaks due to missing DTD entities).

What’s Next

First of all, there are still a few bugs to fix (you can find a list in the dependencies of the tracking bug). Sadly, there are still several places in the code that assume the language will never change, and cache the translated content too aggressively.

The path forward has yet to be defined. Completing the migration to Fluent would drastically improve the user experience:

• Language switching would be completely restartless.
• Firefox would support a list of fallback locales. With the old technology, if a translation is missing it can only fall back to English. With Fluent, we can set a fallback chain, for example Ligurian->Italian->English.

There are also areas of the browser that are not covered by language packs, and would need to be rewritten (e.g. the profile manager). For these, the language used always remains the one packaged in the build.

The user experience could also be improved. For example, can we make selecting the language part of a multiplatform onboarding experience? There are a lot of hints that we could take from the host operating system, and prompt the user about installing and selecting a different language. What if the user browses a lot of German content, but he’s using the browser in English? Should we suggest them that it’s possible to switch language?

With Firefox 66 we’re also starting to collect Telemetry data about internationalization settings – take a look at the table at the bottom of about:support – to understand more about our users, and how these changes in Preferences impact language distribution and possibly retention.

For once, Firefox is well ahead of the competition. For example, for Chrome it’s only possible to change language on Windows and Chromebook, while Safari only uses the language of your macOS.

This is the result of an intense cross-team effort. Special thanks to Zibi Braniecki for the initial idea and push, and all the work done under the hood to improve Firefox internationalization infrastructure, Emanuela Damiani for UX, and Mark Striemer for the implementation.

5 responses

Dorah wrote on July 11, 2019 at 7:11 am :

Thanks for your help, I can now add any language I want rather than having to install another version of the app. All thanks to you!!

Fernando wrote on July 13, 2019 at 3:10 am :

My firefox browser is a mess after the last update .
I am in Brazil , but I always use my browser in english .
But right now its half on English and half Portuguese , some times inside the same box .
In options I have all set for English .
How to fix this ?

Francesco Lodolo [:flod] wrote on July 13, 2019 at 5:06 am :

Comments in a blog post are not the best place to get support. There’s SUMO and Bugzilla. Having said that, take a look at this bug.

Heidi wrote on July 15, 2019 at 9:02 am :

I have the same problem. My OS (Windows 10) is in English as are all the other apps, but I’m in a German-speaking country. After painstaking searching and work, I got my Firefox to work in English before, and now I realize it’s messed up again. The browser options are in German, right-click options in German, and tab options a mix of English and German. The browser language settings do nothing because they were already set in English. I’m using Firefox Quantum, v. 68.0.

Francesco Lodolo [:flod] wrote on July 15, 2019 at 9:10 am :

At this point I’m going to close the comments for this post. Please use SUMO to get support.

How to change Firefox language settings

Mozilla Firefox is among the best-known browsers in the United States though Chrome and Safari are much more popular. What sets Firefox apart, is that its source code is open, with a large community continuously working on its development. In terms of usability, the web client also has many advantages: a clear design, regular updates, and a huge amount of available extensions define the browser. The language selection is also generous: Firefox has over 90 options to choose from. But what do you do, if you want to change your selected Firefox language? The following instructions will show you how to change the language in Mozilla Firefox.

Change Firefox language: step-by-step instructions

When you download Firefox, you’re prompted to choose a language. This is the language in which all menus, notifications, and messages will be written. But this choice doesn’t have to last forever, because you can choose to change your Firefox language settings at any time. But how is this done?

Mozilla Firefox offers many configuration options. One of these is the automatic saving of your browser history. This practical function also has a disadvantage, though, because it can mean that strangers can look into your recent search and can lead to outdated page versions to be shown. In our article on how to clear your Firefox browser history, we’ll show you how to delete saved browser activity regularly. It’s also equally important to regularly clear your browser cache.

Step 1: Open settings

Open your Firefox browser and open the menu by clicking on the hamburger icon with the three horizontal lines. In the menu, select “Preferences.”

Select “Preferences” in the Firefox menu.

Step 2: Select “Language”

Your settings will now open in the browser. Scroll down until you reach the headline “Language,” which is where Firefox shows you the language that’s currently selected. To change your Firefox browser language, click on the downward-pointing arrows:

To change the language of Firefox, click on your current language selection.

Step 3: Available languages

In the drop-down menu, you’ll now see which languages have already been selected as browser languages. If the language you’re looking for is listed, you can continue with step 5. If it’s not on the list, click on “Search for more languages…” and continue with step 4.

Select a language or search for others.

Step 4: Search and add languages

The browser will now open a new window for advanced language settings. Click on “Select a language to add…”

If you want to change your Firefox language, you have 90 languages to choose from.

Next, Firefox will present a list of available languages. Navigate up and down with the arrows to see the languages, which are listed alphabetically. When you’ve found your preferred language, select it with a left-click of the mouse.

Using the arrows, navigate up and down to find your preferred language.

After clicking on your language of choice, it will be shown in the lower, greyed-out area. Next, click on “Add.”

Click on “Add” to add a new Firefox language.

Step 5: Select new language

The new language will now appear in the list above to be selected as the standard language. Select the language again (with a left mouse click) and confirm your selection by clicking on “OK.”

Add a new language by selecting it and confirming by clicking on “OK.”

Step 6: Restart Firefox

In the general Firefox preferences, you should now see your newly-selected language. To confirm all changes, click on “Apply and Restart,” which will prompt the browser to automatically close and restart. After this, all menus and notifications will be shown in your new language.

Click on “Apply and Restart” for your language changes to take effect.

Make sure to save anything that’s open, since the Firefox restart may mean losing unsaved data.

Change Firefox language: compact overview

To change your Firefox language settings, follow the steps as outlined in our quick overview:

1. In your browser menu, open “Preferences.”
2. Scroll down until you reach “Language.”
3. Open the drop-down menu by clicking on your currently selected language.
   • If your preferred language is already being displayed, select it and jump to step 5.
   • If not, continue with step 4.
4. Click on “Search for more languages…”
   • If the language you’re looking for is missing, click on “Select a language to add…”
   • Use the arrows to find a language before selecting it. Confirm by clicking on “Add.”
5. To make the language your browser language, click on “OK.”
6. For your language preferences to take effect, click on “Apply and Restart.” Once your browser has restarted, all menus and notifications will be shown in the new language.

Clear Firefox history: Here’s how

Sites you’ve visited, active logins, individual website settings – Firefox provides you with the option of saving any user data in the browser-specific history, but this practical feature always comes with the risk that such information could end up in the wrong hands. We’ll show you how to counter this risk, and clear your Firefox history.

How-to in Firefox: Export bookmarks

You may need to export your Firefox bookmarks to an HTML file if you want to import them later or use them in another browser. That way you won’t have to transfer your Firefox bookmarks manually, saving you a lot of time compared to moving them over one by one. We’ll show you how to export Firefox bookmarks with just a few clicks.

Firefox: Import bookmarks with ease

The feature that allows you to import Firefox bookmarks all at once can save you a lot of time. It’s tedious to transfer these items manually if you’re using a new computer or you’ve decided to switch to the Firefox browser. However, all it takes is a few clicks to import your bookmarks to Firefox once you’ve exported them. We’ll show you how it’s done.

Firefox private browsing – what is it and how do you turn it on?

Surf the web without leaving a trail – that’s possible in Firefox using “private mode.” It’s quick to activate and can be used temporarily or permanently. Here’s a quick guide on Firefox’s incognito mode, explaining which data is actually concealed (and which data isn’t).