Firefox Translations: Firefox's offline translate feature is making progress

Martin Brinkmann
May 30, 2022
Updated • Jun 3, 2022
Added link to official Mozilla Add-ons page.
Firefox add-ons

Firefox Translations, Firefox's privacy friendly built-in translate feature, has reached a new milestone with the release of a new add-on version.

Translate functionality that is built-into the web browser was introduced by Google and its Chrome web browser. You had to install browser extensions before that or rely on manual translations before that.

firefox translate

Most translate services require an Internet connection to work. Google Chrome communicates with the company's Google Translate service to return translated content to the user. While that is handy, some users dislike the privacy implications of translate services.


Some browser makers have integrated privacy-friendly translate services as a response. Vivaldi Technologies, maker of the Vivaldi browser, integrated such a service in Vivaldi 4.3. Instead of using a cloud-based third-party service or untrusted translate feature, Vivaldi Technologies is hosting its own translate service instance.

The holy grail from a privacy perspective is a browser that supports local translations that do not require an Internet connection at all. Mozilla has been working on that for some time now for its Firefox web browser. Mozilla integrated Firefox Translations in the Nightly version of the browser in mid 2021, but it stopped working eventually and little information was released on the status of the project.

Mozilla continued its work on Firefox Translations in the background. A new version has been released some days ago that improves the functionality significantly. If you read the 2021 article on the integration in Firefox, you may remember that Firefox Translations supported only a handful of languages at the time. It could be used to translate English, Spanish and Estonian, and English into German.

firefox translate local

Firefox Translations 1.1.2 introduces support for additional languages. Right now, English, Bulgarian, Czech, Estonian, German, Italian, Norwegian Bokmål, Portuguese and Spanish are supported fully. The languages Icelandic, Norwegian Nynorsk, Persian and Russian are listed as beta.

Firefox Translations adds an icon to the browser's address bar; a click on the icon displays a toolbar that resembles the translate toolbar of other browsers. Since Firefox Translations is running all translate jobs locally, it is necessary to download language packs that power the functionality.

When a user selects a language for the first time, its language pack is downloaded to the local system. Once downloaded, Firefox will identify the language automatically. The system language is not displayed as a translate source. If Firefox is in English, you won't get translate options to translate English pages to another language, only the other way around.

Besides improved language support, work on improving the performance of the translate feature has continued. There is room for improvement, as there is a noticeable delay between hitting the translate button and receiving the translated page. It took a second or two in tests, but mileage may vary. Translation quality was excellent, but more tests are required to assess the quality and compare it to translations by popular online services.

Mozilla added several other improvements in the latest version. Firefox Translations supports Apple Silicon Chip devices, the translations of forums, and the highlighting of translate errors. Firefox users may also enable the automatic translation of selected languages.

The latest Firefox Translations add-on is available on GitHub. It can be installed in Nightly and Developer editions of the web browser. Users need to set the preference xpinstall.signatures.required to FALSE and the preference extensions.experiments.enabled to TRUE on about:config to install the add-on in the browser.

Closing Words

Built-in translate functionality that is privacy friendly could give Firefox a much needed boost once it is integrated into the stable version of the browser. There is no fixed date yet. Mozilla still has work to do, including adding more languages and improving the performance of the service further.

Now You: will you use Firefox Translations when it is released? (via Sören Hentzschel)

Firefox Translations: Firefox's offline translate feature is making progress
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Firefox Translations: Firefox's offline translate feature is making progress
Firefox Translations, Firefox's privacy friendly built-in translate feature, has reached a new milestone with the release of a new add-on version.
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  1. John G. said on May 30, 2022 at 11:18 am

    One of the best things that Chrome/Edge have is the feature to translate all foreing language websites by their own easily and with some accurate results. Firefox needs an addon, now I have one by Filipe Ps that it the only one that worked fine for me, translating even all Twitter posts (not available at Chromium).

    1. Mikhoul said on May 30, 2022 at 6:12 pm

      >> (not available at Chromium).

      I use it on Chromium/Brave since many months:

  2. Tom Hawack said on May 30, 2022 at 12:29 pm

    Interpreters, translators, dictionaries. Translation requires interpretation, mainly in literature though less in common sentences and perhaps not at all in scientific domains.

    Dictionaries are by themselves not all equal and users, academics will promote one rather than another.
    Translation attempts to combine the obvious dictionary element with, within the interpretation of the sentence, the paragraph and sometimes of a complete book.

    The hard part is always the interpretation, this is what qualifies a good translation, this is what i.e. differentiates Yandex Translation from Bing Translation from Google Translation from DeepL, in increasing quality order.

    Now, will I use Firefox Translations when it is released? I’ll give it a try of course but if the result is closer to Yandex Translation than to DeepL I’ll likely forget it, otherwise will be welcomed.

    At this time I refer to several dictionaries and when it comes to translation either manual input on the DeepL website either via a dedicated extension named ‘Tra,slate Web Pages’ which is IMO a pure gem.

    1. nicolaasjan said on May 30, 2022 at 3:01 pm

      > either via a dedicated extension named ‘Translate Web Pages’ which is IMO a pure gem.

      This extension hasn’t seen any update since 9 months.
      There are however some newer commits to the repo on GitHub.

      I hope it will survive Manifest v3…

      1. Tom Hawack said on May 30, 2022 at 3:53 pm

        @nicolaasjan, if indeed ‘Translate Web Pages’ on AMO is nine months old, it’s version is 9.4.2 (2021-09-14) whilst the latest version on the GitHub repo is 9.4.1 (2021-09-03) …

        As you I hope anything alive will survive MV3. Hope is perhaps acceptable with Firefox.

      2. Shiva said on May 30, 2022 at 7:02 pm

        My goodness, you are making me worry about Manifest v3 which I have never read in depth. Why an extension like ‘Translate web pages’, which I use with pleasure, should not survive?

      3. nicolaasjan said on May 30, 2022 at 8:50 pm

        Well, at least on Chromium and thus on Chrome as well, Google will just disable MV2 extensions after Jan. 2023 (except limited enterprise exceptions).
        See timeline here:

        So developers will have to update their extensions.
        Abandoned extensions will be removed from the store and stop working in your browser.

        I don’t know if Mozilla will do the same.
        Couldn’t find a clear statement.

      4. Hitomi said on May 30, 2022 at 7:31 pm

        They already said they keep all the features exposed that manifest v3 is trying to castrate. Checkmate Alphabet and Chromekeks.

      5. Shiva said on May 30, 2022 at 9:54 pm

        Good. While it last.

        I guess there is a difference between the need of updating the extension and the inability to maintain some core features. I hope this is the first case. There is a post on the GitHub repository of ‘Translate Web Pages’ which also link to ‘Single File’ extension but I have not read it thoroughly:

  3. ECJ said on May 30, 2022 at 1:58 pm

    Sounds great – translation is something I use regularly and I’m not keen on third-party extensions.

    The article mentions translating full pages, however something I also use a lot in Microsoft Edge is selecting specific text (such as text in a single tweet for example) and going to [Right-click > Translate selection to English]. It would be good if Firefox also offers this capability as well.

  4. Anonymous said on May 30, 2022 at 4:26 pm

    Just how long have Firefox/Mozilla promised this?

    Every time they give an update, everything is progressing well, only a matter of time and then…..(insert tumbelweeds gif)

    1. Hitomi said on May 30, 2022 at 7:01 pm

      IH sockpuppet ftw! Glad to see you in every firefox topic.

      1. Iron Heart said on May 31, 2022 at 1:31 pm


        Dude, I never write under any other pseudonym than “Iron Heart” here. Why would I? What would be the benefit?

        You should check whether or not you suffer from paranoia. Sure seems like it.

        PS: I am not waiting for any Firefox feature as I don’t use that crap in the first place.

  5. G said on May 30, 2022 at 5:11 pm

    Are they using neural network for offline translate ?

    1. owl said on June 4, 2022 at 7:21 am

      This add-on,
      Firefox Translations – Extension for Firefox
      “Firefox Translations” is developed under the European Union-funded Project Bergamot.
      Mozilla releases local machine translation tools as part of Project Bergamot

      Instead of the “GPU” conventionally required for deep learning associated with machine translation, Mozilla developed a new API centered around the machine translation engine, ported it to WebAssembly, and optimized the matrix multiplication operations to run efficiently on the CPU.
      This allows not only the development of translation add-ons, but also the integration of local machine translation on all web pages, allowing users to perform free-form translation without using the cloud.

      1. owl said on June 4, 2022 at 7:26 am

        > Are they using neural network for offline translate ?

        In January of 2019, Mozilla joined the University of Edinburgh, Charles University, University of Sheffield and University of Tartu as part of a project funded by the European Union called Project Bergamot. The ultimate goal of this consortium was to build a set of neural machine translation tools that would enable Mozilla to develop a website translation add-on that operates locally, i.e. the engines, language models and in-page translation algorithms would need to reside and be executed entirely in the user’s computer, so none of the data would be sent to the cloud, making it entirely private.

  6. Mothy said on May 30, 2022 at 5:56 pm

    I do not care for or want built-in translate functions (or installing any browser extensions). I just want a web browser to display webpages.

    Instead for translation functionality I use QTranslate (portable version) which has options to use various online translation services (ex. Google, Microsoft, DeepL, etc.) which I have found work a lot better than any offline function due to their neural network features. I understand the privacy implications of using such online services. But it’s a tradeoff I’m willing to make to get the best possible translation.

    I also like that QTranslate has a history feature of all translations as well as an option to save them which can be very useful if you wish to review prior translations or archive a conversation you had with someone. Also it can be used on any application not just the web browser.

  7. Paul(us) said on May 30, 2022 at 7:01 pm

    Martin, nice article.
    But still what I do not understand (can’t make out) are two things.
    To which other addon or program I can compare it?
    Is it maybe more like Or is it more like Grammerly?
    Is it better dan Is it better than Grammerly?

    I think that an offline dictionary/spelling program is much safer.

    1. Martin Brinkmann said on May 31, 2022 at 6:53 am

      Firefox Translations is like Google Translate, Microsoft Translate or DeepL, but without talking to the cloud when it comes to translations. Internet connectivity is required to download the language packs, but that is about it. It is not a grammar checker or spell checker.

  8. Anonymous said on May 30, 2022 at 7:14 pm

    Anything for Firefox that can translate Twitch chats?

  9. nitro322 said on May 31, 2022 at 5:29 pm

    I really like the idea of this. Would love to see it mature. Unfortunately, looks like it’s still a ways off for me as I primarily need to translate Japanese, which doesn’t seem to be even on the roadmap yet.

    In the meantime I’ve been using, which I see a few others have mentioned. It works well, and I love that I can set it to auto-translate certain sites based on domain names. Only thing I don’t care for is the dependency on Google and Yandex – being able to do the translation locally would be perfect.

    Hope to see this project continue.

  10. Ray said on June 1, 2022 at 1:42 am

    This is one of the most promising additions to Firefox in a long time. Can’t wait for this to be ready!

  11. rulol said on June 1, 2022 at 7:24 pm

    Yandex Translate app for Android is very good, and they don’t have any leverage in Western World, so no worry MIB will come knock on your door. :)

  12. owl said on June 4, 2022 at 8:50 am

    > Now You: will you use Firefox Translations when it is released?

    Of course, I intend to use Japanese once it is supported.
    As a Japanese, I am currently using the desktop version of DeepL regularly, and adding the browser extension Simple Translate as a complementary to the browser.

    Firefox Translations,
    The development concept and story (history and progress) are legitimate, and I have been following the development status since the beginning. In layman’s terms, I thought it would be difficult for the language packs and translation speed of offline specifications to reach a practical level, so it is surprising that they were able to release a product in just 3 years (In January 2019, with Project Bergamot). Naturally, since it is in its early stages, the number of supported languages is small, but the all-important “translation speed and translation quality” seem to be well received.
    Above all, the fact that “the engine, language model, and in-page translation algorithm all reside on the user’s computer and performed translation” and do not transmit data externally is a definite difference (advantages) from any other “translation feature”.
    This is a hot topic in Japan,

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