Privacy Policy

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Local-First & Private: Cycle Sister is built with a local-first architecture. This means your personal health information is stored entirely on your device and is not collected, sold, or shared with us.

1. Introduction

Welcome to Cycle Sister ("we," "our," or "us"). We are committed to protecting your privacy. This Privacy Policy explains how we collect, use, and safeguard your information when you use our mobile application (the "App").

Please read this policy carefully. By downloading, accessing, or using the App, you agree to the terms of this Privacy Policy.

2. Information We Collect

Local Storage

A. Personal Health Information

We do NOT collect, transfer, or upload your menstrual cycle history, ovulation logs, symptoms, moods, safe windows, or profile names to any remote servers. All calculations, predictions, and profile records are stored and processed 100% locally on your device in a secure SQLite database.

Third-Party SDKs

B. Automatically Collected Information

Depending on your subscription tier, the App may integrate third-party services that automatically collect technical data:

Google Mobile Ads (AdMob): If you use the free version of Cycle Sister, Google's AdMob SDK is used to display advertisements. AdMob may collect and use device identifiers (such as Android Advertising ID or iOS IDFA), IP addresses, and diagnostic info to personalize ads, verify delivery, and perform analytics.
App Stores (Google Play / Apple App Store Billing): When purchasing premium subscriptions, transactions are processed directly by Google Play or Apple App Store. We do not collect or store your billing credentials, bank details, or credit card numbers.

3. Local Backups & Data Sync

You can choose to back up your local data manually. Backups are encrypted locally on your device using a password you choose. When you export or sync your encrypted backup files, they remain securely encrypted with your password. We cannot access your backup file contents or recover your backup password if it is lost.

4. Subscription Features & Ad Blocking

We offer Monthly and Yearly subscription options ("Premium Plan"). When subscribed:

Google Mobile Ads SDK is bypassed and ads are completely removed.
Predicted safe windows in the calendar are unlocked and calculated locally.
Multi-profile support is enabled, allowing you to manage multiple members locally.

5. Data Retention

Since your health data is stored entirely on your device, it remains on your device until you delete the App or clear the App's storage cache. Uninstalling the App deletes all local databases, profiles, and logs. Be sure to export an encrypted backup if you wish to retain your data.

6. Third-Party Service Links

The App may contain links to our Privacy Policy website or external resources. We are not responsible for the privacy practices of external websites. We encourage you to read the privacy statements of any website you visit.

7. Children's Privacy

Our App is not intended for use by children under the age of 13. We do not knowingly collect personal information from children under 13. If you believe a child has provided us with personal information, please contact us so we can take immediate action to remove any accidentally collected information.

8. Changes to This Privacy Policy

We may update our Privacy Policy from time to time. We will notify you of any changes by posting the new Privacy Policy within the App or on our official store listings. You are advised to review this page periodically for any changes.

9. Contact Us

If you have any questions or suggestions regarding our Privacy Policy, please contact us at:

Email: support@cloudspirit.co.uk

Last Updated: June 5, 2026