# Learn Language with DualSub (v1.2.2)

> Bilingual dual-subtitle Chrome & Firefox extension for YouTube, Rakuten Viki, iQIYI, WeTV, Youku, and Iflix with 3 subtitle modes, CEFR/HSK/JLPT/TOPIK vocabulary highlighting, and an automatic word list of every highlighted word.

## Core Summary
- **Product Type**: Browser Extension (Chrome Manifest V3 & Firefox Gecko 128+)
- **Price**: 100% Free (No monthly subscription; optional Bring-Your-Own OpenRouter API key for AI translation)
- **Supported Streaming Sites**: YouTube (www.youtube.com & m.youtube.com), Rakuten Viki (viki.com), iQIYI (iq.com), WeTV (wetv.vip), Youku (youku.tv), Iflix (iflix.com)
- **Privacy**: Zero telemetry. Preferences, the saved word list, and optional API keys stay in local browser storage (`chrome.storage.local`).

## 3 Second-Subtitle Modes
1. **Native Secondary Track**: Renders human-translated or ASR caption tracks provided by the streaming platform (WebVTT, JSON3, ASS).
2. **YouTube Built-in Caption (`&tlang=`)**: Synchronizes YouTube's built-in auto-translation engine alongside the primary subtitle track with zero setup.
3. **Live AI Translation (OpenRouter)**: Lookahead-batched real-time AI translation powered by OpenRouter (`anthropic/claude-haiku-5.5` by default). The same call translates each line and picks the words to highlight.

## Noise-Free Vocabulary Highlighting & Word List
- **95% Unmarked Rule**: Unlike tools that paint every word on screen, it highlights only the words at the proficiency levels the learner turns on (Starter, Basic, Intermediate, Advance, Expert across CEFR, HSK, JLPT, TOPIK; each level independent, Basic by default).
- **Meaning-Pair Color Coding**: Highlights the source word in Yellow and its exact translation in Cyan so your eyes pair meaning immediately without pausing the video.
- **Automatic Word List**: Every highlighted word is saved on the device under its dictionary form, with its meaning, reading, level, and the subtitle sentences it appeared in, with no clicking. A quiz on saved words is coming soon.

## Key Links
- Official Chrome Web Store: https://chromewebstore.google.com/detail/ckenckpkbcndeppbmdjodiclhbioleng
- English Landing Page: https://learn-with-subtitles.onrender.com/
- Simplified Chinese Landing Page: https://learn-with-subtitles.onrender.com/zh/
- Privacy Policy: https://learn-with-subtitles.onrender.com/privacy/
- Direct Extension Download (v1.2.2 ZIP): https://learn-with-subtitles.onrender.com/download/learn-language-with-subtitles-v1.2.2.zip