berga-translator от Reimu

Translate anything in your browser using Bergamot and Firefox Translations Models - just highlight, right click, and select "Translate Selection".

Fully usable offline once models are downloaded and set up.

There are a few key differences between this extension and the official
Firefox Translations extension:

• This extension focuses on translating user-selected parts of text
• The official extension attempts to translate the entire page
• This extension lets you change what languages to translate between
• The official extension does not let you change the language and only works if it initially, properly detects a page's language
• This extension allows you to upload and save models directly to it (hence unlimited client side data)
• The official extension downloads the models off Google Cloud. This means it requires an update when new models are created
• A fancy UI?