HappySubs — Dual Subtitles & Live Captions: YouTube™, Vimeo, Zoom, Bilibili

Dual subtitles on YouTube, Vimeo, Bilibili and Zoom recordings. Translate captions, read both languages together, export .srt.

Dual subtitles on YouTube, Vimeo, Bilibili and Zoom recordings — two languages on one line, and captions for videos that have none. 【HOW IT WORKS】 On YouTube, turn on the player's captions (the CC button) and HappySubs translates them, showing the original and the translation together as a single subtitle. On Vimeo, Bilibili and Zoom cloud recordings it reads the subtitle track or transcript directly, so there is nothing to switch on. It uses the video's own subtitles when they exist and free Google Translate otherwise. No account, no sign-in, no setup. It also works on more sites such as Coursera: click the HappySubs icon on the page, and you can let it start by itself there from then on. For videos with no subtitles at all, optional live transcription listens to the audio and writes the captions itself. Recognition runs on your own computer, so the audio never leaves it — and it costs nothing to run. It needs a small local program you install once; everything else works without it. It understands spoken Chinese, English, Japanese, Korean and Cantonese. 【FEATURES】 • Works on YouTube, Vimeo, Bilibili and Zoom cloud recordings, including YouTube and Vimeo players embedded in other sites • Zoom recordings: bilingual subtitles from the recording's own transcript, a translation under each paragraph of the Audio Transcript panel, and a bilingual transcript export with speakers and timestamps • More sites such as Coursera: click the icon to get bilingual subtitles • Both languages as one subtitle: they appear and change together, once per sentence • Dual subtitles on any video with captions, auto-generated included — read as whole sentences, not words scrolling in • Human-authored subtitle tracks preferred, machine ones as fallback • Free Google Translate by default; optional AI translation with Claude, OpenAI, Gemini or DeepSeek using your own API key — and you choose the model • Paid APIs are never called without your explicit confirmation • Live transcription for videos with no subtitle track (spoken Chinese, English, Japanese, Korean and Cantonese; runs locally), translated a whole sentence at a time — optionally by your own AI translator and key • Translation-only mode: read just the translation with the player's captions closed • Download subtitles as .srt — both languages, the original alone, or the translation alone — or as a readable bilingual transcript • One shortcut turns the second language on and off without opening the popup: ⌘⇧S, or Alt+Shift+S on Windows and Linux • Style the original and the translation separately, or lock them together; position, size, colour, background and width are all adjustable, and you can drag the subtitle itself, fullscreen included • The subtitle moves clear of the player's controls when you pause • 100+ target languages • Interface in English, Chinese (Simplified and Traditional), Japanese or Vietnamese 【PRIVACY】 Open source. The extension reads the current video's subtitles and sends that text to the translation service you choose. API keys stay in your browser's storage. With live transcription switched on, audio goes only to the recogniser on your own machine over a loopback connection — never uploaded, never sent to the developer. It never uses your microphone, and there is no tracking or analytics of any kind. On sites outside the supported list it runs only when you click its icon. MORE INFO: https://huanshuowang.com/happysubs/