Mozilla is now offering translation extension called Firefox Translations of its own for the Firefox web browser. This extension is not like any other translation extension that were available until today. Firefox Translations downloads some initial data for a language translation and then does the entire translation locally. This makes the translations very fast as the dependency on any cloud or online sources has been removed.
After you have installed the Firefox Translations extension in your Firefox web browser, it becomes ready as soon as you visit a website that is not in your local language. This is when the add-on bar appears on the top of the website. You can choose the language of the website and it will start to translate it into your local language. There is also an option to automatically translate all the webpages from that open open tab. We can also translate web forms using this extension.
As of now Firefox Translations does not have many options. In the extension options, we can choose to send some statistics to Mozilla so that they can improve the features in the future. Right now there are some languages supported such as English, Spanish, Estonian, Czech, German, Norwegian, Italian, Bulgarian Portuguese, etc. There are many more languages in the production chain such as Russian, Icelandic etc.
Benefit of local translation by Firefox Translations is privacy. Because all the translation is done at the local level on the client side, none of the text is sent over the cloud. This ensures the privacy of the user who is visiting a website. But on the other side, since the translation is done locally, it could be a tad slow depending on the system performance. A computer with faster CPU and more RAM is definitely going to do translations faster.
You can download Firefox Translations extension from https://addons.mozilla.org/en-US/firefox/addon/firefox-translations/.