Subz intelligently detects uncommon vocabulary in real-time captions, delivers instant 0ms definitions with pronunciation, and builds your personal vocabulary notebook—without ever breaking your flow.
Click the amber underlined words in the subtitle below to test the instant card popover and pronunciation in action.
"We need to dissect the subtle nuances of this sentence."
Zero AI sparkles. Zero robotic generic definitions. Just seamless vocabulary acquisition.
Every word is checked against a 10,000+ word database. Only uncommon, high-yield vocabulary is highlighted. Everyday words (e.g. remember, change, operate) and tech brands are never falsely flagged.
While you read the subtitle line, Subz pre-warms definitions in background memory. By the time you click, the definition appears in 0 milliseconds with zero network delay.
Dual-speed pronunciation pills (1.0x and 0.75x) let you train your ear to catch natural native phonetics and word stresses in conversational English.
Subz hooks directly into YouTube’s video controller. Click Resume or Replay 5s to seamlessly rewind and continue playback without video desync or pauses.
Save any word with its in-scene context quote. Build a lasting daily habit with our 5-word goal progress bar and streak tracker in the popup dashboard.
Take your vocabulary anywhere. Export your complete study sheet with definitions, parts of speech, and dialogue context to a clean text file for Anki, Notion, or paper study.
Add Subz to Chrome in one click. Open any YouTube podcast, interview, or tutorial with English captions.
Subz unobtrusively underlines uncommon words in Subz Amber without interrupting your movie or lecture.
Click any word to reveal its simple definition, listen to native audio, bookmark it, and hit Resume!
Your saved words, learning streaks, and preferences never leave your browser. Subz has no external tracking scripts, requires no account login, and never collects your browsing history. Everything is stored locally on your device.
