Open-source YouTube Chinese translation and dubbing extension.
Effective date: July 23, 2026
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LocalTube Dub is an open-source Chrome extension that translates, transcribes, and dubs the active YouTube video. It has no LocalTube Dub account system, advertising, analytics, payment processing, or hosted translation service.
This policy covers the Chrome extension and the optional LocalTube Dub Engine installed on the same computer.
LocalTube Dub’s use and transfer of information received from Google APIs and Chrome extension permissions adheres to the Chrome Web Store User Data Policy, including the Limited Use requirements. LocalTube Dub uses this information only to provide or improve its disclosed single purpose, does not sell it, does not use it for advertising or creditworthiness, and does not allow humans to read it except where permitted by that policy.
To provide its single purpose, LocalTube Dub may handle:
LocalTube Dub does not use this data for advertising, profiling, credit decisions, or sale to third parties.
Non-secret preferences are stored with chrome.storage.sync. If the user has Chrome Sync enabled, Chrome may synchronize those preferences through the user’s Google account. API keys are excluded from sync and stored only in chrome.storage.local.
The optional caption cache is also stored in chrome.storage.local. It may contain the YouTube video ID, language identifiers, caption text, translated text, cue timestamps, and the Provider/model identity used for an AI translation. It does not contain video, audio, cookies, or API keys. Cache entries expire after seven days and are limited to 12 timelines or approximately 4 MB. Users can disable caching or select Clear caption cache at any time.
Removing the extension clears its Chrome extension storage. The optional desktop Engine keeps runtime files, logs, models, and user-requested exports separately on the computer. Its uninstall command removes the runtime; the --purge option also removes Engine caches and logs. Local Whisper models are retained unless the user deletes them.
The extension communicates with YouTube only for the active video. It first uses caption information already available to the current page, then may request the active video’s caption or player data from YouTube. It does not monitor unrelated browsing pages.
When the optional Engine uses yt-dlp, it first attempts public caption access. If YouTube requires authentication or a bot check, the Engine may ask yt-dlp to read the local Chrome YouTube session and send the necessary request back to YouTube for the active video. YouTube cookies are not sent to LocalTube Dub, AI Providers, or Microsoft text-to-speech. Advanced users can disable browser-cookie fallback with the Engine setting documented in README.md.
When Chrome local translation is selected, translation is performed by Chrome’s on-device Translator API. LocalTube Dub does not send caption text to a third-party translation Provider in this mode. Chrome may download the required language pack.
When a user selects a cloud Provider, the extension sends caption text directly to that Provider’s authorized HTTPS origin using the API key supplied by the user. Supported choices include Microsoft Translator, Google Cloud Translation, OpenAI, Gemini, Claude, DeepSeek, OpenRouter, and a user-configured OpenAI-compatible endpoint.
Cloud hosts are optional Chrome permissions. The extension requests access only after a direct user choice, derives the exact origin for the selected Provider, and checks that permission again before transmitting data. Provider requests are governed by the selected Provider’s terms and privacy policy.
When an optional local translator such as Ollama is selected, caption text is sent only to the loopback Engine or the local Ollama endpoint on the same computer.
No-caption transcription is disabled unless the user enables it. Local transcription sends an audio-only segment to the loopback Engine, where whisper.cpp and FFmpeg process it on the same computer.
If a user selects Groq, Deepgram, or OpenAI transcription, the captured audio segment is sent directly to that selected Provider with the user’s API key. If direct player capture is unavailable, the extension may request optional tabCapture and offscreen permissions and record a bounded portion of the active YouTube tab. It does not record background tabs or unrelated sites.
The default Microsoft natural online speech mode sends only the translated subtitle text being spoken, the selected voice, and speech-rate settings through the companion Engine to Microsoft Edge’s text-to-speech service. It does not send the source video, captured audio, API keys, YouTube cookies, or unrelated browsing history.
Selecting local system voice generates speech with the operating system’s local speech service and stops sending subtitle text to Microsoft text-to-speech. Chrome browser speech may be used as a local playback fallback when Engine speech is unavailable.
The Chrome extension communicates with the optional Engine through Chrome Native Messaging or the loopback addresses 127.0.0.1 and localhost. LocalTube Dub does not operate a remote Engine server. Temporary media used by local transcription or rendering is deleted when processing completes; user-requested exported audio remains until the user deletes it.
LocalTube Dub does not sell user data. Data is transferred only as necessary to provide the feature and mode explicitly selected by the user, to comply with law, or to address a security issue. LocalTube Dub does not retain a server-side copy because it does not operate a hosted backend.
The public project, privacy, and support pages are hosted by GitHub Pages. GitHub may process visitor information, including IP-address logs, under the GitHub Privacy Statement. LocalTube Dub does not add analytics or advertising trackers to these pages.
Third-party Providers and platforms may retain requests under their own policies. Users should review the terms of YouTube, Chrome, Microsoft text-to-speech, and any API Provider they select.
Users can:
LocalTube Dub is a general-purpose developer tool and is not directed to children. It does not knowingly collect children’s personal information.
Material privacy changes will be documented in CHANGELOG.md, reflected in this policy, and submitted with the corresponding Chrome Web Store update when required.
Open a support or privacy issue in the public source repository. For a vulnerability or a report containing sensitive information, use the repository’s private vulnerability-reporting process.