There are 36 pages of translation extensions. The official one works without the cloud, which is pretty unique.

Personally I like the Immersive Translate extension. You can select your preferred translation engine (cloud based, but it supports many) and it shows you both the translated text and original text by alternating the paragraphs.

Sadly the only thing it's lacking. Saw a couple of years ago they were looking at different technologies to implement it client side for privacy reasons.

Before post edit:
While looking for the source i found this:
Firefox Tests Privacy-Friendly Web Page Translations

It's coming bby!

@NamesArrHard @clearleaf, better than a extension is to use this one for Desktop, so you can use it independent of the browser.
It's FOSS, multiengine for 125 languages, customizable shortcuts, Windows and Linux

https://crow-translate.github.io

simple translate