*For a limited set of languages. Until they add Japanese I won’t be getting much use from it, sadly.
I use 10ten (previously Rikuchamp) for Japanese. I don’t think it does full translation, but it gives thorough dictionary lookups (from WWWJDIC) as mouseover tooltips. Very useful if you’re trying to learn the language, but maybe not so much if you just want to read stuff quickly. I think it’s now available for every major browser, but I mostly use it on FF.
Firefox has translation now, too, on both mobile and desktop.
And you can optionally add the Google Translate extension to desktop Firefox if you want. (It really is convenient, isn’t it?)
And you can always just plug in the URL of whatever page you’re trying to translate directly into https://translate.google.com/.
AFAIK the built-in translator doesn’t support Japanese, which is 99% of translation I need and the extension (which is what is was trying to use before) either requires you to select the text that you want to translate one-by-one or run the whole page through translate.google.com, which doesn’t work with any page that requires an account to access or triggers ddos protection on some others.
