Download and install the Translatium extension for PopClip or your browser:

PopClip extension PopClip Google Chrome extension Chrome Safari extension Safari Microsoft Edge extension Edge Firefox Firefox Opera extension Opera Brave extension Brave Vivaldi extension Vivaldi

The extensions are free, open-source and do not read or alter the websites you visit, or collect data from you.

Because of technical limitations [1], [2], the extensions are incompatible with Linux and only work with Mac or Windows PC.
PopClip and Browser Extensions