Select any text, translate it, and have it read aloud — or dub any captioned video into your language with one click. Entirely powered by Chrome's native, on-device AI; works on regular web pages and inside Chrome's built-in PDF viewer.
▶ Install from the Chrome Web Store
Everything runs locally in the browser:
- Translation → built-in
Translator+LanguageDetectorAPIs - Speech → native
chrome.ttsAPI
No account, no server, no analytics. Nothing you watch or select leaves the machine.
Settings and the toolbar popup:
The floating panel reading a translation aloud:
- Right-click → VoiceOne on any selected text:
- Auto Read Original Language — reads the selection aloud in its own language.
- Translate & Read ▸ <language> — translate into one of ~15 languages and read it.
- One-click video dubbing — re-narrates any captioned video in the language you choose: the original audio ducks down and the video's captions are spoken in sync by a clean TTS voice, translated on-device when needed. A small on-page panel lets you switch the dub language live, adjust how loud the original stays, and stop. No downloads, no external services, no waiting.
- Works beyond YouTube (new in 1.3) — dubbing runs on other video sites too, enabled by you, one site at a time. See Supported sites.
- Floating control panel with Pause · Resume · Repeat · Stop · Clear · ✕ and a live
status line (e.g.
Translated mixed → fr · Google français). Drag it by the header. - Toolbar popup mirrors the panel, controls dubbing on any enabled site, and works as a fallback control surface.
- Settings in a side panel (new in 1.3) — preferences open alongside the page instead of in a separate tab: voice, rate, pitch, volume, default target language, the original-audio level while dubbing, and which languages appear in the menu — including adding your own language (name + ISO code + optional voice locale) beyond the built-in set.
| Site | How captions are read | Dub button |
|---|---|---|
| YouTube | Dedicated adapter (InnerTube caption API) | In the player controls |
| Vimeo | Dedicated adapter (player config + WebVTT) | Toolbar popup |
| Dailymotion | Dedicated adapter (player metadata, incl. embedded players) | Toolbar popup |
| Bilibili | Dedicated adapter (subtitle JSON; usually needs you to be logged in) | Toolbar popup |
| Any other site | Generic adapter — the page's standard HTML5 caption tracks | Toolbar popup |
YouTube works out of the box. Every other site is opt-in: open the toolbar popup on that site
and click Enable dubbing on this site. Chrome asks once, you approve, and dubbing works there
from then on — including after a browser restart. Revoking the site later from
chrome://extensions cleanly turns it back off.
This is deliberate. VoiceOne ships with activeTab only — no standing permission to read your
browsing. Sites are granted individually, by you, and only the ones you actually use.
The generic adapter works on any page whose video exposes real caption tracks. Some sites serve captions through a private API instead, and those need their own adapter — if a site you care about says "no captions found on this page", open an issue with the URL.
The dub re-narrates the video's caption track (auto-generated or manual — virtually every instructional video has one), synchronized to the player clock. If the video already has a caption track in your chosen language, it's used directly — no translation step at all. That means:
- It's a clear neutral TTS voice, not a clone of the original speaker's voice.
- A video with no captions at all can't be dubbed (you'll get a clear message).
- Caption transcription errors pass through to the narration.
- Live streams aren't supported.
- Google Chrome 138 or newer (built-in AI APIs).
- Chrome's on-device translation models download on first use of a language pair (you'll see a "Downloading model… %" status). If a model or language pair isn't available, VoiceOne tells you and (where possible) reads the original text instead.
From the Chrome Web Store (recommended): chromewebstore.google.com/detail/voiceone
Or load the source (for development):
- Download or clone this repository.
- Open
chrome://extensions. - Toggle Developer mode (top-right).
- Click Load unpacked and select the
VoiceOnefolder. - (For local PDFs via
file://) click Details on VoiceOne and enable Allow access to file URLs.
Selections (any page or PDF):
- Select text on any page (or in a PDF).
- Right-click → VoiceOne → Auto Read Original Language or Translate & Read ▸ a language.
- The floating panel appears, shows the (translated) text, and reads it aloud. Use the panel or the toolbar popup to pause/resume/repeat/stop.
Dubbing on YouTube:
- Open any YouTube video with captions.
- Click the VoiceOne logo button in the player's bottom-right controls.
- The original audio ducks down and a clear voice narrates in sync. Videos in another language show a brief on-device "Translating… %" pass first.
- Use the VoiceOne dub panel (bottom-left) to switch the dub language live, adjust how loud the original audio stays, or stop (✕). Clicking the player button again also stops.
Dubbing anywhere else:
- Open the video and click the VoiceOne toolbar icon.
- Click Enable dubbing on this site and approve Chrome's prompt (once per site).
- Press Start dubbing in the popup. The same dub panel appears on the page.
Defaults for both live in Settings → Video dubbing.
| File | Role |
|---|---|
manifest.json |
MV3 manifest, permissions, menu |
background.js |
Service worker: menus, detection, translation, chrome.tts, panel state |
panel.js |
Floating control panel injected into the page (Shadow DOM) |
lib/dub-engine.js |
Site-agnostic dub engine: synced narration, audio duck, dub panel, translation batching |
youtube.js |
YouTube site adapter: dub button, caption fetch, ad detection, SPA-navigation glue |
sites/generic.js |
Adapter for every other site: HTML5 caption tracks + Vimeo / Dailymotion / Bilibili |
popup.html / popup.js |
Toolbar popup, dub controls, per-site enablement |
options.html / options.js |
Preferences side panel (chrome.storage.sync) |
lib/languages.js |
Language list + TTS hints |
lib/captions.js |
Caption parsers: YouTube json3/srv3, WebVTT, SRT, Bilibili JSON |
icons/ |
Toolbar/store icons |
Adding a site means writing a getCues() for it in sites/generic.js and registering its
hostname — the engine, panel, and popup controls come for free.
- "No on-device model for X → Y" — that language pair isn't supported by the built-in Translator on your Chrome build; try another target or update Chrome.
- "no captions found on this page" — the video has no caption track VoiceOne can read, or the site serves captions through a private API that needs its own adapter.
- Bilibili says subtitles can't be found — most Bilibili subtitles are only served to logged-in users; sign in and reload.
- Panel doesn't appear over a PDF — use the toolbar popup, which mirrors the same controls and status.
- No voice / wrong language voice — install or pick a voice in Settings; some languages use Chrome's online "Google" voices, which need a network connection.
- "VoiceOne was updated — reload this page" — after installing or reloading the extension, tabs that were already open keep the old script; refresh the tab once (the popup offers a Reload video tab button).
- "couldn't load captions" — YouTube occasionally gates caption requests; reload the page and try again, or try another video.
- More site adapters, driven by what people actually ask for.
- Better voices, per-language voice preferences.
Released under the MIT License © 2026 Rohit Waghire.
VoiceOne is a local-first demo of Chrome's built-in AI.