Two subtitles at once.

Watch any YouTube video with the original line and your language, together — on iPhone and iPad.

Translated by AI, not by YouTube

Real sentences that read naturally, instead of the word-by-word machine translation YouTube hands you.

Twenty languages

Pick the language you are learning in, and switch it any time. The interface itself speaks twelve.

Follow along, word by word

The line being spoken scrolls into place, and the current word lights up as you hear it.

Readable the way you want

Text size, colour of each line, and subtitle position — adjustable, and adjustable while the video is full screen.

Free and Pro

 FreePro
AI-translated videos3 a dayUnlimited
Out of translationsWait until tomorrowNever happens

DuoSub is free to use for as long as you like. Pro is a subscription billed by the App Store and can be cancelled at any time.

Requirements

iOS 17 or later. Videos must have captions on YouTube — DuoSub reads the captions that are already there, it does not transcribe audio.