LectureSub is a free, open-source Chrome extension that helps you learn courses on Udemy with bilingual subtitles, look up meanings, and save vocabulary while watching lectures.

Main features:

• Display bilingual subtitles, the original text only, or the translation only.
• Click on a word in the original subtitles to look up its meaning; optionally pause the video while looking up and resume when closing the meaning box.
• Save words along with their meanings, the original sentence, the lesson, and the timestamp for review.
• Search in the vocabulary notebook and export a CSV file for use with Anki, Excel, or Google Sheets.
• Customize font, font size, colors, background, and subtitle position.

No separate account or API key is required. The extension uses the built-in translator in Chrome; settings and vocabulary notebook are stored locally on the machine.

Requires Chrome on desktop version 138 or higher and Udemy lectures with source subtitles. Translation capability depends on the language pair and device; the extension does not create subtitles from speech.

LectureSub is an independent project and is not affiliated with Udemy.
Homepage: https://lecturesub.congphan.dev
Source code: https://github.com/cong85010/lecturesub-for-udemy