Twinsubs
Watch foreign-language videos and streams with live subtitles in your language
You open a video or a live stream in a language you do not speak. There are no subtitles, or they are in the wrong language, and you want to understand it now. Twinsubs runs live translation on your own Mac: whatever sound this Mac is playing is detected, translated into the language you picked, and shown as two lines floating over the picture, the translation above the original. No waiting for someone to add subtitles, no downloading the video first, no switching windows, no account.
When it helps
- A foreign-language video with no subtitles: a product demo, a tech talk, a keynote, an interview or a documentary where the author added no captions, or only in a language you cannot read.
- A foreign-language live stream: a stream will not wait for you, and nobody is adding subtitles. As the sound comes out, the translation follows.
- Web video, such as YouTube, in a browser: it does not matter which site, as long as the sound plays from this Mac.
- When a platform's own subtitle translation falls short: the video has no automatic captions, the language you need is missing, or you want to watch the same way in every browser and player.
- Content you would rather not upload: the sound stays on your Mac, and both recognition and translation happen there.
When a platform already offers captions and translation you can use, use those first: they are ready-made and free. Live translation is for videos with no captions, the wrong caption language, live streams, and players of every kind.
How to use it: one minute
- Turn on live translation and pick your languageThe first time, it downloads a speech model once (under 1 GB), macOS asks for permission, and it may offer to download a translation language pack. The source language is detected for you; you only choose the language you want to read.
- Pick the sound sourceChoose “All Sounds”, or just one app such as your browser or player so notification sounds from other apps stay out. If you are not sure, choose All Sounds.
- Press play as usualThe caption floats over the picture: the translation on the top line, the original below. To look back, expand the caption for a time-ordered record you can save as txt or SRT.
Compared with what you do today
| Approach | What you do | What is inconvenient |
|---|---|---|
| Wait for a subtitle team or the author to add captions | Wait | A live stream cannot wait, and you do not decide whether captions exist or in which language |
| A platform's own automatic captions and translation | Turn them on | Depends on whether the video has captions and whether the platform offers your language |
| Download the video, then run a subtitle tool | Download, wait, import into a player | Many steps, and no use for a live stream |
| Twinsubs live translation | Turn it on and watch | Machine translation makes mistakes, and the caption appears a moment after the sound |
If the video is already on your disk and you want to rewatch it or edit it, drop it into Twinsubs for an SRT file: see generate subtitles from a video. For a bilingual SRT of a foreign-language video, see add bilingual subtitles to a video.
Which languages it understands and translates into
- Understands: English, Chinese, Cantonese, Japanese, Korean, German, French, Spanish, Italian, Portuguese, Hindi and more. The language is detected automatically, and if it changes midway the caption follows.
- Translates into: 20 target languages. Which pairs are available depends on Apple's on-device translation, and the first time you translate a language macOS may ask you to download its language pack.
- Works offline: once the speech model and the translation language pack have been downloaded, recognition and translation both run on your Mac without a connection.
For a fuller picture, including how it differs from cloud live translation, see live translation app for Mac. For meetings, see live translation for meetings; for courses, see subtitles for online courses and lectures.
Limits, stated up front
- The sound has to be hearable: the app listens to the sound this Mac plays, which needs the system's permission. For some copy-protected content the system may not let an app hear the sound, and then there are no captions. We have not tested platforms one by one, so we name none and promise nothing.
- Machines make mistakes: more so with heavy accents, loud background music, people talking over each other and technical terms. For numbers and names, trust the original.
- Captions lag a little: it has to hear a short stretch before it can recognize and translate it, so the translation appears slightly after the speech.
- What it does not do: it does not read the translation aloud, tell speakers apart in computer sound, or save anything for you.
- Allowance: the free version covers 10 minutes per day of live translation; a one-time purchase removes the limit, with no subscription.
- System: a Mac with macOS 26 or later, Apple silicon.
Privacy: the sound stays on your Mac
- On-device: the sound is used for recognition and translation on your Mac only. Nothing is uploaded and there is no backend.
- No recording, nothing saved: caption text is not kept by default. To keep it, save the expanded record yourself as txt or SRT, wherever you like.
- Analytics without content: the app's anonymous usage statistics contain no caption text or file names. See the privacy policy.
FAQ
Can it translate web video such as YouTube?
Yes. Sound from a video playing in a browser is, like any other sound, sound this Mac plays, and choosing All Sounds is the easiest way. If the platform's own caption translation works for you, use that first.
Can it translate a live stream as it happens?
Yes. Live translation handles the sound playing right now, so nothing has to be saved first. The caption appears a moment after the speech because it has to hear a short stretch first.
The video already has subtitles. Do I still need it?
Not if there are subtitles you can read. It is for videos with no subtitles, the wrong subtitle language, and live streams.
Does it work for every platform's videos?
We cannot promise that. The app listens to the sound this Mac plays, which needs the system's permission, and some copy-protected content may not be hearable. We have not tested platforms one by one, so we do not name any.
Does it work offline?
Yes, as long as the speech model and the translation language pack have been downloaded once. After that, recognition and translation both run on your Mac without a connection.
Is the sound uploaded?
No. Recognition and translation both run on your Mac. There is no backend, so the sound never passes through a server. The first launch needs a connection to download the speech model once, and macOS downloads the translation language packs.
Is the free version enough?
The free version covers 10 minutes per day of live translation, which is enough to try it. To use it all the time you need the one-time purchase, with no subscription and no limit on videos or live translation.
Can I keep the translation?
Yes. The expanded caption is a time-ordered record of originals and translations that you can save as txt or SRT. Nothing is saved by default.
Updated 2026-10-12. Back to the Twinsubs home page