SubText guide
How to install, what each part of the extension does, and where every setting lives.
Quick start
Install SubText
One-click install from the Chrome Web Store or Firefox Add-ons. No account needed for the free tier.
Open any supported video
With our extension installed and enabled, open a video on one of our supported platforms. Hit play on a video with captions — SubText should attach automatically.
Hover or click for translation
Mouse over a word for an instant tooltip; click for a full lookup card with definition, word class, and an example. The video keeps playing.
Upgrade for AI features
A paid tier unlocks AI translation, idiom explanations, and your personal library.
Watching videos
Display
Controls how the dual-caption overlay looks on the player — font size, vertical position, opacity, and the overall subtitle layout.
Word Hover
Configures the on-hover translation tooltip — font size, color, how long to wait before resuming the video, how to handle potential alternative meanings.
Lookup
Click a word or select a phrase to open a detailed lookup card. The Lookup tab controls what shows in the card (definition, word class, example, etc.), and whether each lookup auto-saves to your library.
Idioms
When AI mode is on, idioms in the dialogue can be optionally highlighted inline so you can click for an explanation in your native language. This tab controls the highlight's color and opacity, whether learned idioms still get highlighted, and how much surrounding dialogue the AI considers when explaining each one.
Customizing
General
Settings scope — whether changes apply globally across every site, or only to the current one. Useful when one video platform needs different defaults than another. The General tab is also the place you select your main translation mode, the language you want captions to be translated in, how long subtitles should be, what your learning languages are, how many captions you want to pre-translate, how much context each caption should be sent with for translation, and your preferred translation style.
Shortcuts
Keyboard shortcuts for navigating subtitles, skipping through the video, and adjusting playback speed. Shortcuts are rebindable.
Controls
Which optional SubText buttons appear in the player UI — the playback speed buttons, token usage indicator, and subtitle position lock.
Appearance
Menu font size, menu theme, and menu opacity.
Account
Account
Account sign-in and fallback handling when credits are exhausted.
System
Reset all settings to defaults, or reset only the current site's overrides. Useful when an experimental tweak made something worse and you don't remember what you changed.
Ready to try it?
Install free. Open any supported video. You're already past step 2.