SubTech — AI Captions

Generate AI captions for videos in your browser.

SubTech adds accurate, AI-generated captions to videos while you watch — no downloads, no copy-pasting links, no leaving the page. Open a video, click SubTech, and press "Generate captions." Our AI transcribes the audio and lays perfectly synced captions right over the video player. Want them in your language? Pick from 120+ translation languages and the captions arrive translated. Supported on 100+ websites. 1. Sign in (email or Google) — new accounts start with free credits. 2. Open a page with a video, such as bilibili. 3. Click the SubTech icon and press "Generate captions." 4. Watch the progress of transcription. 5. Captions appear over the video, synced to playback. That's it. FEATURES • AI transcription — accurate captions generated from the video's audio • Translation into 120+ languages, from Spanish and Japanese to Zulu • Captions render directly over the video and stay in sync — seeking, pausing, and fullscreen all work • Make it yours: adjust caption font, size, color, background opacity, and position on the video • Set a default translation language once — every session starts ready to go • Accidentally refreshed the page? Reopen SubTech and your captions come back instantly, without re-transcribing • Clear, staged progress with the ability to cancel anytime