Instant translation
Native subtitles translated the moment they appear. Zero setup, no account, no waiting.
Live demo — subtitles update as you watch
Any video. Your language.
PolySub overlays live-translated dual subtitles on YouTube and any video site — the original stays, your language joins it, synced to the second.
Free to install — all six themes included. Sign up to sync presets and use transcripts.
Today we're making handmade ramen from scratch.
วันนี้เราจะทำราเมงทำมือตั้งแต่ต้น
12:04 / 24:30
What is PolySub?
PolySub reads the subtitles a video already has — or transcribes speech live — and translates on the fly. Original and translation sit together on the video, so you never lose the voice of the person speaking.
- ✓Works on YouTube and any video site with subtitles
- ✓Dual lines — original on top, your language below
- ✓Captions when none exist, via Live Transcribe
- ✓Six free themes for a comfortable watch
More than a translation overlay
From the first subtitle to a saved phrase, PolySub keeps every part of your watch session in one place.
AI that gets nuance
PolySub AI handles slang, jokes, and honorifics. Pro includes 2,000 credits each month — about 20 hours of video.
Live Transcribe
No subtitles? PolySub writes captions from speech in real time — and translates them too.
Word lookup
Hover any word to pause, hear it, and see what it means in context. Save it to your list.
Searchable transcript
Search every caption, make private corrections, and export your own transcript.
Yours, everywhere
All six themes are free. Your languages, themes, and presets sync to every device you sign in on.
Watching in three steps
- 01
Add to Chrome
One click. Open any video — YouTube works out of the box.
- 02
Pick your language
Instant translation starts the moment you choose.
- 03
Go Pro when ready
Upgrade only when you want AI translation or Live Transcribe.
A theme for every mood
Pick a palette to preview how PolySub can look while you watch.
I missed you so much.คิดถึงมากเลยนะ
Quick answers
Do I need an account to use PolySub?
No — instant translation and all themes work the moment you install. An account adds transcript tools and sync.
What happens when Pro credits run out?
Instant translation keeps working without limits. You can add non-expiring top-up credits or buy another Pro period.
Which sites does it work on?
YouTube out of the box, plus any video site with native subtitles. Live Transcribe covers videos with no subtitles at all.