Naruhodo — Privacy Policy

Last updated: February 10, 2026

Overview

Naruhodo is a Chrome extension that helps you read Japanese by providing furigana and word lookups. We are committed to protecting your privacy. This policy describes what data the extension processes and how it is handled.

Data That Stays on Your Device

The following data is stored locally in your browser and is never transmitted to any server:

• Vocabulary bank — Words you save, including the word, reading, definition, source sentence, page URL, page title, tags, and save timestamp. Stored in chrome.storage.local.
• Extension settings — Your preferences such as hover mode on/off. Stored in chrome.storage.local.
• Dictionary data — The bundled JMdict dictionary (215,000+ entries) loaded into IndexedDB on first install. This data is shipped with the extension, not downloaded from the internet.
• Page content analysis — When you visit a Japanese web page, the extension reads text on the page to provide furigana and hover lookups. This text is processed entirely within your browser.

Data Sent to External Services

The extension does not send any data to external servers. All processing — dictionary lookups, tokenization, furigana generation — happens entirely within your browser.

Data We Do Not Collect

• We do not collect personal information (name, email, etc.).
• We do not collect browsing history or page URLs (except what you explicitly save to your local vocabulary bank).
• We do not use analytics, tracking pixels, or any third-party tracking services.
• We do not sell, share, or transfer any data to third parties for advertising or any other purpose.

Permissions

The extension requests the following browser permissions:

• All URLs (host_permissions) — The content script must run on any web page to detect Japanese text and provide reading assistance.
• Storage — To save your vocabulary bank and preferences locally.
• Unlimited Storage — The bundled dictionary is approximately 30 MB and requires more than the default storage quota.
• Active Tab — To communicate with the current tab for furigana and hover features.
• Offscreen — To run the dictionary and tokenizer in a background document for performance.

Data Retention and Deletion

All locally stored data (vocabulary bank, settings) can be deleted by:

• Removing individual words from the vocabulary bank.
• Uninstalling the extension, which removes all extension storage.

Changes to This Policy

If we make changes to this privacy policy, we will update the "Last updated" date above. Continued use of the extension after changes constitutes acceptance of the updated policy.

Contact

If you have questions about this privacy policy, please open an issue at github.com/hanashi42/naruhodo/issues.