InterSub

InterSub is a dual subtitles extension and translator extension designed for language learning. It integrates with popular browsers to display two lines of subtitles—one original and one translated—alongside a pop-up dictionary. The tool targets learners who watch video content across streaming platforms and courses, providing an environment where language practice fits into viewing time.

The extension operates inside the browser, showing dual subtitles and offering instant translations when users hover over unfamiliar words. Words looked up are saved in a personal Wordbook, creating a growing vocabulary that can be reviewed later. Access to the Wordbook and translations is tied to the user’s InterSub account and extension settings.

InterSub supports a wide range of platforms and languages, including courses from Coursera, Udemy and LinkedIn Learning, plus streaming services like Netflix, YouTube, Prime Video, and others. It emphasizes immersion by letting users learn while watching familiar shows and courses, with AI translation features available on paid plans.

Plans, platforms, integrations and limits are outlined on the pricing and install pages. The service works in Chrome, Edge and Firefox, with coming Safari/mobile support noted. Free and paid tiers exist, with AI subtitle translation tied to paid tiers and a trial period available. The service also discusses offline usage constraints and remote-control features for mobile access.

Use cases

• Language learning while watching
• On-page translation and word lookup