Twinsubs
Live translation on Mac: translate audio as it plays
You are watching a foreign-language stream, or a course with no subtitles, and want to follow it right now. Twinsubs' live translation runs on your own Mac: sound from any app has its language detected and is translated live into the language you choose, with the original and the translation stacked into two lines over what you are watching. Recognition and translation both happen on this computer.
Where it helps
- Foreign-language streams and videos with no subtitles: in a browser or a player, as long as the sound comes out of this Mac.
- Meetings: Zoom, Teams, Webex and Google Meet all work, with no host to enable it and no meeting-app plan; see bilingual subtitles for meetings.
- Online courses and lectures: read the translation and the original together while you watch; see subtitles for courses and lectures.
- What it does not do: it does not speak the translation aloud (no voice interpreting), does not write minutes, and does not separate speakers within the computer sound.
How to use it
- Turn on live translationThe first time, the speech model downloads once; macOS asks for your permission and may offer to download a translation language pack.
- Choose the audio sourcePick “All Sounds”, or just one app, so other apps' alert sounds do not end up in the caption. To add your own voice, turn on the microphone too, and “me” and “them” are shown separately.
- Choose the target languageThe source language is detected automatically; you choose the target.
- Watch, or meet, as usualA floating caption appears on screen with the original and the translation stacked in two lines. To look back, expand it: you get a time-ordered record that you can save yourself as txt or SRT.
Which sounds and languages it handles
- Sound: whatever any app plays, in a browser, a player or a meeting app. “All Sounds” covers the whole Mac; picking one app translates only that app.
- Languages it 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.
- Languages it translates into: 20 target languages. The available language pairs depend on what Apple's on-device translation supports, and macOS may ask you to download a language pack the first time you use one.
- 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.
Local versus cloud live translation
Most translators put the original on the left and the translation on the right, in a window you have to switch to. Twinsubs stacks the two into a two-line caption that floats over whatever you are watching, so your eyes never leave the video.
That is the difference in how it is shown. How it is processed differs too, between local and cloud:
| Twinsubs (on your Mac) | Cloud live translation (in general) | |
|---|---|---|
| Where the sound goes | It stays on your Mac: recognition and translation both run on this computer, with no server involved | The sound is sent to the provider's servers to be processed |
| How it is charged | One-time purchase, not billed by the minute; the free version gives 10 minutes per day | Often billed by usage time or by subscription; check each vendor |
| Account and API key | None needed | An account is usually required |
| Where the translation appears | Stacked in two lines over whatever you are watching, no window to switch to | Depends on the product |
The right-hand column describes cloud products in general, not any one vendor; check each vendor's own site. For a comparison with specific tools, see the comparison page.
Privacy: the sound stays on your Mac
- Processed on your Mac: the sound is used on this computer only for recognition and translation, and is not uploaded.
- No recording, nothing saved: caption text is not kept by default. To keep it, save it yourself as txt or SRT from the expanded record, in a place you choose.
- Statistics contain no content: the app's anonymous usage statistics contain no caption text or file names; see the Privacy Policy.
Other people speak in what you play. Before you use it, follow the rules of your organization, the meeting and your region; if you plan to save the text, tell the people present first.
Limits, stated up front
- Allowance: the free version gives 10 minutes of live translation per day; the one-time purchase removes the limit, with no subscription.
- System: it needs a Mac with macOS 26 or later, Apple silicon.
- Accuracy: machine recognition and translation make mistakes, especially with heavy accents, background music, people talking over each other and a lot of specialist terms. For important numbers and names, trust the original.
- What it cannot do: it does not speak the translation, and it does not separate speakers within the computer sound.
FAQ
Which sound does it translate?
Whatever this Mac plays: a browser, a player or a meeting app. You can pick the sound of the whole computer, or just one app.
Which languages does it handle?
It understands English, Chinese, Cantonese, Japanese, Korean, German, French, Spanish, Italian, Portuguese, Hindi and more, and translates into 20 target languages. The available language pairs depend on what Apple's on-device translation supports.
What if the language changes partway through?
The language is detected automatically, so if it changes partway through, the caption follows it into the new language.
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.
Does it record or save anything?
It does not record. Caption text is not saved by default; to keep it, save it yourself as txt or SRT from the expanded record.
Is the free version enough?
The free version gives 10 minutes of live translation per day, which is good for trying it out. To use it all the time you need the one-time purchase (no subscription; videos and live translation both unlimited).
How is it different from subtitles for a video file?
Subtitles for a video file process a file you drop in, and give you an SRT file beside the video. Live translation processes the sound that is playing now; the caption floats on screen and no file is created unless you save one yourself. Both are in the same app.
What Mac do I need?
A Mac with macOS 26 or later, Apple silicon. Translation uses the on-device translation built into macOS, and the language pack, once downloaded, is used on your Mac.
Updated 2026-10-12. Back to the Twinsubs home page