edit: Thanks for all the recommendations!
It provides pretty good translations, but it’s not particularly good for privacy. Obviously it’s better than Google, but their privacy policy isn’t great.
My main issue is they want credit card info to get an API key, which is required if you want to use it through (properly integrated) addons or whatever. The translations are pretty much magic though. Really good results most of the time.
- Lingva is a private frontend for Google translate
- LibreTranslate is an independent, free, libre, open-source translation solution
- Translate You is an Android app that allows you to connect to various translation APIs, including Lingva and LibreTranslate
- Firefox Translate allows you to translate websites when using Firefox or LibreWolf
There’s also mozilla.github.io/translate which is Firefox Translate but as a website like Google Translate
LibreTranslate is an option if you’re looking for something open source.
Translate You features LibreTranslate, Lingva, DeepL, MyMemory, Reverso, and SimplyTranslate.
While I can’t speak for any of them, I think that all of those should be safe being that Translate You is FOSS, and their idealogy is “No Ads, no trackers, just You”
Firefox translate seems pretty good