lasDoscas - YouTube™ Dual Subtitles

Sync bilingual subtitles on any subtitle-enabled YouTube video. Free, optional AI translation, fully customizable style.

Hi! This is the first Chrome extension I've ever made, built with a simple goal: to make watching YouTube videos in another language, or learning a new language, a little easier and more enjoyable. lasDoscas Bilingual Subtitles shows the original and translated subtitles together, in sync: below the player in default view and theater mode, or at the bottom of the screen in full screen, just like native captions. Both languages, right in front of you. Want even better translations? Turn on optional AI enhancement using your own free API key from Google Gemini, Groq, or OpenRouter. Free, lightweight, and built to feel right at home on YouTube. ✨ FEATURES - Dual Subtitles, Always in Sync Works on any YouTube video that has subtitles. The original text and its translation appear together in real time, so you don't lose context while watching. Subtitles stay in sync even after you seek, change videos, or switch caption tracks. - Manual and Auto-Generated Captions Works with manually created captions or YouTube's auto-generated captions, cleaned up to reduce repeated words and flicker. - Smart Translation, 55 Languages Translations are generated automatically, with support for 55 target languages, including English, Chinese (Simplified & Traditional), Spanish, French, German, Japanese, Korean, Arabic, Hindi, Russian, and more. On a new install, lasDoscas picks a sensible default from your browser language. - Optional AI Enhancement (New!) Add your own free API key from Google Gemini, Groq, or OpenRouter, and lasDoscas will use AI to translate captions more naturally, using context from nearby lines to better handle pronouns, names, and idioms. AI is off by default and completely optional. If it's ever unavailable, standard translation keeps working without interruption. - Works in Every View Fully adapted for default view, theater mode, and full-screen mode. Switch views anytime and the dual subtitles adjust right along with you. - Controls Inside the YouTube Player Use the lasDoscas switch next to YouTube's own player controls to turn bilingual subtitles on or off. Tap the AI button to turn AI enhancement on or off and see its status. Select the lasDoscas icon to open settings without leaving the video. - Copy the Current Caption Hover over the subtitle panel and select the copy icon to copy the current caption with its timestamp. Hold Shift while selecting it to also include the video title, publication date, video link, and timestamped caption. - Fully Customizable Style Choose a font, show or hide either subtitle row, and adjust size, weight, and color—including separate settings for full-screen mode, with three background styles and adjustable opacity. - Settings Save Immediately Changes apply and save right away—no Apply button needed. Reset comes with a short undo window. - Native UI Integration The subtitle cards are designed to match YouTube's own interface, in both light and dark themes. - Trilingual Interface The extension popup is available in English, Simplified Chinese, and Spanish. 📖 HOW TO USE 1. Open a YouTube video that has captions. 2. In YouTube's caption menu, choose an original caption track or an auto-generated track (not YouTube's own "Auto-translate" track—lasDoscas needs the original captions to work). 3. Turn on lasDoscas from the player switch or the extension popup. 4. Open settings, choose your target language, and adjust how the subtitles look. 5. Optional: turn on AI enhancement, pick Gemini, Groq, or OpenRouter, and paste in your API key. 🔑 GET A FREE API KEY AI enhancement needs your own API key—it's free to get one from any of these providers: - Google Gemini: aistudio.google.com - Groq: groq.com - OpenRouter: openrouter.ai Just sign up on the provider's site, create a key, and paste it into lasDoscas. By default, your key is only kept for your current browser session. Turn on "Remember key on this device" if you want it saved for next time. Your key is only ever sent to the AI provider you chose—never to YouTube or anyone else. ⌨️ KEYBOARD SHORTCUT Shift + Alt + S (Shift + Option + S on Mac) — show or hide the settings panel in full-screen mode. 🌐 COMPATIBILITY Works on Chrome, Edge, Brave, Opera, Vivaldi, and other Chromium-based browsers. 🔒 PRIVACY FIRST lasDoscas doesn't collect accounts, browsing history, or usage data. Your settings, styles, API keys, and translation cache are all saved locally on your device. To show subtitles, the extension reads caption and video info from YouTube. When AI enhancement is on, the current caption and a few nearby lines are sent to the AI provider you chose—so their privacy terms and any usage limits apply. 🆓 lasDoscas is completely free, open-source, and ad-free—no account needed. AI enhancement is optional; the AI providers may require their own free account. This is a personal project, made and maintained by one developer. If you run into any issues or have suggestions, I'd genuinely appreciate your feedback—it helps a lot. lasDoscas is an independent, open-source project and is not affiliated with or endorsed by YouTube, Google, Groq, OpenRouter, or any AI provider. 💡 Tip: lasDoscas only works on YouTube video pages and needs an available caption track. If subtitles don't appear, try refreshing the page. 📋 All 55 supported target languages: English, 中文（简体）, 中文（繁体）, español, français, français (Canada), Deutsch, 日本語, 한국어, português, Indonesia, Melayu, русский, العربية, हिन्दी, தமிழ், ไทย, Tiếng Việt, Türkçe, polski, Nederlands, svenska, dansk, norsk, suomi, italiano, română, magyar, čeština, hrvatski, Ελληνικά, עברית, Filipino, українська, euskara, català, galego, íslenska, Kiswahili, eesti, latviešu, lietuvių, slovenčina, slovenščina, български, српски, اردو, فارسی, मराठी, বাংলা, ગુજરાતી, తెలుగు, ಕನ್ನಡ, മലയാളം, አማርኛ