Zotero

« This is an add-on for Zotero 6. It provides PDF translation for Zotero built-in PDF reader.

Once you have the plugin installed simply, open any PDF in your collections.

Select some text, the translation are shown.

If Automatically Translation is disabled, use shortcut T or click button to translate selected text.

Not the lauguage you want? The default tartget lauguage is zh-CN(Chinese Simplified). You can edit it in the Preference menu… ».