LinguaSub — Real-time Translated Subtitles

Real-time on-device subtitles for any video. Auto language detection, local AI translation, fullscreen, customizable styles.

LinguaSub brings real-time, on-device translated subtitles to ANY video on the web. ★ HOW IT WORKS 1. Open any video (YouTube, Netflix, Bilibili, online courses, video calls…) 2. Click the LinguaSub icon and pick your target language 3. Press "Start on this tab" — captions appear instantly over the video ★ KEY FEATURES • Auto language detection — just choose the language you want to read • 100% on-device AI — Whisper for speech recognition + NLLB for translation • No audio leaves your browser. Your data stays private. • Works in fullscreen — subtitles follow the video even in fullscreen mode • Fully customizable styles — font, size, color, background, position, opacity, outline, shadow • Bilingual display — original text and translation shown together ★ PRIVACY FIRST All processing happens locally in your browser using WebGPU/WASM-accelerated AI models. We never upload, store, or transmit your audio or captions to any server. Note: First run downloads AI models (~600MB) from Hugging Face; they are cached afterward.