Privacy policy

Applies to the Chinese Brain browser extension for Firefox and Chrome. Last updated November 9, 2026.

Chinese Brain keeps your data in your browser. It has no account, no analytics, and no server of its own. Your word list, settings and API keys are stored locally (browser storage) and are never sent to the developer.

What leaves your browser

Some features send data to third-party services, only to perform the feature:

• Reading words and sentences aloud (default voice): the text is sent to Google's text-to-speech service (translate.google.com) when you press V or a play button.
• English subtitle line on YouTube: when YouTube does not provide an English translation, the video's Chinese caption lines are sent to Google Translate (translate.googleapis.com).
• Looking up a selection: when you select Chinese text and ask for its card (Option key or right-click menu) and it is not a single dictionary word, the selected text is sent to Google Translate (translate.googleapis.com) for its English translation.
• Azure voice (optional, your own key): the text you play is sent to Microsoft Azure Speech in the region you choose.
• Gemini (optional, your own key): when you press "Subtitles with Gemini", the YouTube video's link is sent to the Google Gemini API; when you press "Write example sentences", the word and its short meaning are sent. On Google's free tier, Google may use these requests to improve its models.
• Image search: pressing I opens a DuckDuckGo image search for the word in a new tab.

Nothing else leaves your browser. The text of the pages you read is used only on your device to find words; it is not collected, sold or shared.

Deleting your data

Uninstalling the extension deletes its data. You can also export or clear your word list from the extension's word-list page.

Contact

Questions about privacy: use the support link on the extension's page in Firefox Add-ons or the Chrome Web Store.