Privacy Policy

Introduction

Kestrel is a vocabulary spaced-repetition app developed by James Ward. This policy describes how the app handles information.

Summary: We Do Not Collect Your Data

Kestrel does not transmit your personal data off your device to the developer or to third parties. This matches the App Store Data Not Collected label for the app.

Information Stored on Your Device

The app keeps the following data locally on your device only:

• FSRS scheduling state per vocabulary card
• Review history and grade log
• Active language pair, topic filter, and inventory reconciliation settings
• Subscription entitlement cache for offline access (derived from Apple; not payment details)
• Session counter, if enabled (on device only)
• Bundled vocabulary Inventory (static content in the app package; not user-specific)

How We Use On-Device Information

On-device data is used solely to run the app: build review queues, apply spaced repetition, remember your preferences, and gate free versus paid content. It is never sent to developer servers.

Accounts

Kestrel has no user accounts, login, or cloud sync. There is no server-side profile to access or delete.

Subscriptions and Payments

Purchases and renewals are handled entirely by Apple via StoreKit. The developer does not receive or store payment card or billing details. See Apple’s Privacy Policy. You can cancel or manage your subscription in Apple ID settings or via Manage Subscription in the app.

Text-to-Speech

L2 word audio is generated on your device with Apple’s speech synthesis. No audio recordings are sent to the developer.

Third-Party Sharing

We do not sell, rent, or share user data with third parties. Kestrel does not include third-party analytics, advertising, or tracking SDKs.

Data Retention and Deletion

On-device data remains until you remove it. To erase all app data, delete Kestrel from your device (and use iOS “Delete App Data” if offered). There is no developer-held server copy to request deletion, and no in-app account-deletion flow because there are no accounts.

Children

Kestrel is not directed at children under 13, and we do not knowingly collect personal information from anyone.

Open-Data Attribution

Lemma frequency ordering draws on Google Books Ngram datasets (CC BY 3.0) and, where used, Leipzig Corpora Collection word lists (CC BY 4.0).

Changes to This Policy

Last updated: September 14, 2026. We may update this page; material changes will be reflected by updating the date. Continued use after changes constitutes acceptance.

Contact Us

Privacy questions: [email protected]