InterSub

InterSub is a browser extension that turns your favorite streaming and educational content into a powerful language learning tool. Instead of separate study sessions, you pick up new vocabulary and grammar naturally while watching YouTube, Netflix, Prime Video, Udemy, Coursera, LinkedIn Learning, and TED — with interactive dual subtitles showing your native language alongside the language you're learning. Hover over any word for an instant translation, and InterSub automatically saves the words you've encountered to a personal vocabulary list you can review later. It's the most enjoyable way to build real language skills — because you're actually watching content you love.