Privacy Policy — Bopomofo Reader Extension

Last updated: May 18, 2026

Effective date: May 18, 2026

Privacy Policy for Bopomofo Reader Browser Extension

1. Introduction

Bopomofo Reader Extension (“Bopomofo Reader”, “the Extension”) is designed with privacy-first principles. This Privacy Policy explains what data is processed, where it is processed, and when data may leave your browser.

Developer: code-horse
Contact: 2008-horse@163.com

2. Information We Do NOT Collect

Bopomofo Reader Extension is designed with privacy as a core principle:

No account registration required — You can use all features without creating an account.
No personal data collection — We do not collect, store, or transmit any personal information to external servers.
No analytics or tracking — We do not use any analytics SDKs or tracking tools.
No advertising — The extension contains no advertisements or ad-related tracking.
No browsing history recording — We do not record or transmit the URLs you visit.

3. Data Stored Locally in Your Browser

The Extension stores the following data locally in your browser only (via Chrome Storage API):

Data Type	Purpose	Storage
Extension settings	Preferences (enable/disable, bopomofo style, hover mode, definition language, speech rate, translation engine, target language, PDF detection, etc.)	Browser local storage
UI language preference	Remember your chosen interface language	Browser local storage
PDF banner preference	Remember whether you dismissed the PDF detection banner	Browser local storage
Floating button position	Remember the position of the floating annotation button	Browser local storage

Important: All data listed above exists only in your browser. It is never uploaded to any server. If you uninstall the extension, this data will be permanently deleted.

4. Translation Feature & Third-Party Services

The Extension includes an optional translation feature that sends text to third-party translation services for processing:

Service	Provider	Endpoint	Data Sent
Bing Translate	Microsoft Corporation	`api-edge.cognitive.microsofttranslator.com`	Selected or page text only
Google Translate	Google LLC	`translate.googleapis.com`	Selected or page text only

Important:

Translation is triggered only when you explicitly click the translate button, use the translate keyboard shortcut, or invoke the context menu. Text is never sent automatically.
Only the text being translated is transmitted — no URLs, browsing history, personal data, or other page content is sent.
For Bing Translate, the extension obtains an anonymous authentication token from edge.microsoft.com/translate/auth. This token contains no personal information.
The text is sent directly to the translation provider’s API from the extension’s background service worker. We do not relay, store, or log any translation requests or responses on our servers.
Please refer to Microsoft’s Privacy Statement and Google’s Privacy Policy for details on how these providers handle data.

5. PDF Reader

The Extension includes a built-in PDF reader that adds Bopomofo annotations to PDF documents. When PDF detection is enabled:

The extension uses Chrome’s declarativeNetRequest API to automatically redirect PDF URLs opened in the browser to the built-in PDF viewer.
When viewing a remote PDF, the browser fetches the PDF file directly from the original server — this is standard browser behavior and no data passes through our servers.
The extension may display a browser notification when a PDF is detected, allowing you to open it in the Bopomofo Reader PDF viewer.
All PDF processing (text extraction, bopomofo annotation, dictionary lookup) is performed entirely locally within your browser.

6. Permissions Explained

The Extension requests the following browser permissions:

Permission	Purpose
`storage`	Store user settings (enable/disable state, bopomofo style, hover mode, definition language, speech rate, translation preferences, PDF detection preference, etc.)
`tts`	Use Chrome’s built-in Text-to-Speech to read Chinese pronunciation
`scripting`	Execute scripts in web pages to add bopomofo annotations
`contextMenus`	Add right-click menu options to speak and translate selected text, and open PDFs with Bopomofo Reader
`notifications`	Show a notification when a PDF file is detected, allowing one-click opening in the Bopomofo Reader PDF viewer
`declarativeNetRequest`	Redirect PDF URLs to the built-in Bopomofo Reader PDF viewer when PDF detection is enabled
`declarativeNetRequestWithHostAccess`	Required alongside `declarativeNetRequest` to apply PDF redirect rules across all URLs
`<all_urls>` (host permission)	Add bopomofo annotations to Chinese characters on any webpage; proxy translation requests to third-party APIs from the background service worker; detect and redirect PDF files to the built-in viewer

7. How Bopomofo Processing Works

All bopomofo conversion and dictionary lookup are performed entirely locally within your browser:

The Extension uses the pinyin-pro JavaScript library bundled within the extension, enhanced with modern Chinese dictionary data and Taiwan-pronunciation polyphonic word corrections, then converts pinyin syllables to Zhuyin/Bopomofo locally.
A WebAssembly (WASM) module is used for traditional Chinese character conversion and additional bopomofo corrections — this module runs entirely locally.
Built-in offline dictionaries provide multilingual hover definitions: English from CC-CEDICT, French from CFDICT, German from HanDeDict, and Japanese/Korean/Vietnamese/Chinese definitions from Wiktionary-derived datasets.
Traditional Chinese display and lookup normalization use local conversion when needed.
Chinese character recognition, segmentation (via Intl.Segmenter), and bopomofo annotation all happen on-device.
No text is sent to any external server for bopomofo processing or dictionary lookup.

8. Third-Party Libraries and Open-source Dictionary Attribution

Library / Dataset	Purpose	Data Handling
pinyin-pro	Mandarin pronunciation conversion before local Bopomofo conversion	Runs entirely locally
@pinyin-pro/data/modern	Modern Chinese word pronunciation data	Pre-built data bundled locally
CC-CEDICT	Chinese-English dictionary definitions and base entries	Pre-built data bundled locally
CFDICT	Chinese-French dictionary definitions	Pre-built data bundled locally
HanDeDict	Chinese-German dictionary definitions	Pre-built data bundled locally
Wiktionary-derived datasets via kaikki.org	Japanese, Korean, Vietnamese, and Chinese definition data	Pre-built data bundled locally
OpenCC-js / bundled local conversion module	Simplified/Traditional Chinese conversion	Runs entirely locally
PDF.js (Mozilla)	Render PDF documents	Runs entirely locally

Open-source Dictionary Attribution

Bopomofo Reader bundles offline pronunciation and dictionary resources from open-source or community projects:

Bopomofo conversion data: pinyin-pro and @pinyin-pro/data/modern are used for local Mandarin pronunciation conversion and word-level pronunciation corrections; Bopomofo Reader converts pinyin syllables to Zhuyin/Bopomofo locally and applies Taiwan-pronunciation polyphonic corrections.
Chinese-English dictionary data: CC-CEDICT provides English definitions and base dictionary entries.
Multilingual definition data: CFDICT provides French definitions; HanDeDict provides German definitions; Wiktionary-derived datasets from kaikki.org provide Japanese, Korean, Vietnamese, and Chinese definitions.
Script conversion: OpenCC-js and the bundled local conversion module are used for Simplified/Traditional Chinese conversion when needed.

All dictionary lookups run locally in your browser, and we do not operate a dictionary backend service.

Upstream projects retain their own copyright and license terms. For authoritative licensing details, please refer to each project’s official repository or website.

9. Text-to-Speech

The Extension uses Chrome’s built-in TTS (Text-to-Speech) API:

Speech synthesis is handled by your browser’s built-in engine.
No audio data is recorded or transmitted.
The extension includes tone sandhi and polyphonic character pronunciation optimization, all processed locally.

10. Children’s Privacy

The Extension does not knowingly collect personal information from children under 13 years of age. Since we do not collect any personal information from any users, the Extension is safe for users of all ages.

11. Data Deletion

To remove all Extension data:

Uninstalling the extension will permanently remove all associated settings from your browser.
You can also clear extension data via Chrome Settings > Extensions > Bopomofo Reader > Details > Clear Data.

12. Changes to This Privacy Policy

We may update this Privacy Policy from time to time. Any changes will be reflected in the “Last updated” date at the top of this page.

13. Contact Us

If you have any questions about this Privacy Policy, please contact us at:

Email: 2008-horse@163.com

This privacy policy applies to the Bopomofo Reader browser extension (v1.5.0). For the Bopomofo Reader mobile app privacy policy, please see App Privacy Policy.