Privacy Policy

Last updated: July 18, 2026

1. Introduction

BookHalo (the "Service") is a Chrome extension that uses optical character recognition (OCR) to create personal reading-note text and a reference PDF from pages visible in Kindle Cloud Reader. This policy explains how the Service handles data.

2. Information we handle

• Page images and OCR text: The extension captures pages visible in Kindle Cloud Reader. English, Portuguese, Spanish, French, German, and Italian are normally processed locally in the browser. Japanese pages, or pages for which local OCR fails, are sent to the OCR server.
• Book metadata: ASIN, title, page or location, progress, selected book language, and other information displayed by Kindle Cloud Reader.
• Account information: Your email address and authentication state.
• Payment information: Payments are processed by Stripe. BookHalo does not directly store credit-card numbers.
• Processing and diagnostic records: Page positions, image hashes, character counts, processing duration, job status, browser and book metadata, and error details used for quota management, integrity checks, reliability, and support. When local OCR succeeds, the page image and OCR text body are not stored in BookHalo's cloud systems.
• Website analytics: When you visit book-halo.com, we may record the page path, referring page, acquisition parameters (src, medium, and campaign), browser language, country or region, and a hash of the User-Agent. We do not store the raw IP address in the analytics database.

3. Purposes

• Run OCR and create downloadable reading-note files.
• Avoid duplicate processing and verify page completeness.
• Authenticate users, manage subscriptions, and enforce usage limits.
• Investigate errors, improve reliability, and provide support.
• Measure website usage and acquisition sources.

4. Destinations

• OCR server (ocr.book-halo.com): receives Japanese pages and pages for which local OCR fails, over HTTPS.
• Authentication, billing, and job API (api.book-halo.com): receives account, usage, processing, diagnostic, and website-analytics data. It runs on Cloudflare Workers.
• Stripe: processes subscription and add-on payments. Card details are not stored by BookHalo.

5. Storage and retention

• Local OCR images and text: stored incrementally in browser IndexedDB while the ZIP is being created. They are deleted after download finalization; interrupted local data is automatically removed when it has been stale for more than seven days.
• Server OCR data: retained as needed for OCR, retries, and export creation. Downloadable export artifacts are normally retained for seven days.
• Processing records: book metadata, job state, page positions, hashes, character counts, durations, and error or diagnostic records are stored in the operational database.
• Website analytics: analytics records are normally removed after 180 days.
• Authentication token: stored in Chrome Storage and removed when you log out.

6. Sharing

We do not sell personal data. We share it only with service providers needed to operate the Service, such as Stripe and Cloudflare, or when disclosure is required by law.

7. Browser access and permissions

The extension runs content scripts only on supported Kindle Cloud Reader / Kindle for Web domains. It uses activeTab for visible-tab capture, scripting for Kindle-page interaction, storage for authentication state, and host permissions for supported Kindle and BookHalo server domains.

8. Account deletion

You can request deletion of your account and related account data with the Delete account command in the extension popup.

9. Contact

Questions about this policy can be sent to [email protected].

10. Changes

We may update this policy. Material changes will be reflected on this page with a revised update date.