YouTube Subtitle Word Translator by Pavel

YouTube Subtitle Word Translator makes language learning effortless while watching videos. Simply click any word in YouTube subtitles to see its translation instantly in a tooltip.

Key Features:
• Click-to-translate: Click any subtitle word → instant translation tooltip
• Multiple providers: Google Translate (free), DeepL Free/Pro, LibreTranslate, custom endpoints
• 30 UI languages: English, Russian, Belarusian, German, French, Spanish, Chinese, Japanese, Korean, and more — each displayed in its native script
• Smart CJK support: Chinese/Japanese/Korean text split per-character for precise translation
• Dark mode: Automatic (system) or manual light/dark/theme switching
• Works on: YouTube, YouTube Music, YouTube TV
• Offline caching: LRU cache (500 entries) for instant repeat translations
• Secure: API keys stored locally, optional host permissions for self-hosted endpoints
• No tracking: Zero analytics, zero external requests except translation APIs

Supported Providers:
| Provider | API Key | Notes |
|----------|---------|-------|
| Google Translate | Not required | Free, good quality |
| DeepL Free | Required | High quality, generous free tier |
| DeepL Pro | Required | Best quality, higher limits |
| LibreTranslate | Optional | Self-hostable, privacy-focused |
| Custom endpoint | Optional | Your own LibreTranslate-compatible server |

Privacy First:
• No data collection, no analytics, no tracking
• All settings and cache stored locally in your browser
• API keys never leave your device except to the chosen provider
• Host permission requested only when you configure a custom endpoint

Permissions:
• storage — save settings and translation cache
• host_permissions — YouTube, Google Translate, DeepL, LibreTranslate domains
• optional_permissions — custom endpoint domain (requested on-demand)

Open source (MIT): https://github.com/pvarenik/youtube-subtitle-translator