Subtitle translation
Translate video subtitles
Watch videos with bilingual subtitles. Swiftin reads a video's captions, translates them with the engine you choose, and shows the original and the translation together right over the player, fullscreen too.
Where it works
YouTube
The Swiftin button sits in the player's control row. Works in theater mode and fullscreen.
Coursera
The lecture player, with the same in-player button and overlay.
Netflix
The Netflix player, same button and bilingual overlay over the video.
Three ways to start
In-player button
Click the Swiftin logo in the player's control row to translate the current video.
Hotkey (Alt+V)
Press Alt+V on a video to translate it. Press again to stop. You can change the key in the subtitle menu.
Translate all videos
Flip the toggle at the top of the subtitle menu and every supported video translates automatically, no click needed.
Display modes
Bilingual
The original line and the translation appear together. Pick which one sits on top.
Translation only
Just the translated line, no original.
Original only
The source captions in Swiftin's overlay, with no translation. Useful for following along in the source language.
Make it yours
Subtitle style
Font size, background, and outline, so cues stay readable over any video.
Position
Drag the subtitle block up or down to where you want it. Swiftin remembers the spot.
Download
Export the translated subtitles of the current video as a .vtt file.
Which engine translates
Without an account: Google and Bing. With an account: AI models (Gemini, DeepSeek, Grok) for Pro and Team, or AI on Free while your quota lasts, plus your own key (BYOK). Google and Bing stay as a free fallback.
How the engine cascade worksCommon issues
Each row covers a real case and how to clear it.
CAPTIONS_LIMITEDSubtitles don't load on a video that clearly has them
The platform can temporarily limit how often captions are fetched (especially after lots of quick reloads). Wait a moment and try again, or open another video.
NO_CAPTIONS"No subtitles for this video"
The video has no caption track at all. Swiftin translates existing captions, it does not transcribe audio, so a video with no captions has nothing to work from.
WRONG_LANGTranslated into the wrong language
The subtitle target language is its own setting, separate from page and selection translation. Open the subtitle menu, then Language.
AI_SIGNED_OUTAn AI engine is selected but you're signed out
AI (Plus) engines need an account. Sign in, add your own key for BYOK, or pick "Switch to free" in the alert to use Google or Bing instead.
HOTKEY_CLASHAlt+V does nothing
Another extension or the site itself may use the same shortcut. Change the subtitle hotkey in the subtitle menu.