Short version: Cycle Calendar stores your data only on your own device and in your own Google Calendar. We collect nothing, store nothing on our servers, and sell nothing — because we have no servers.
1. What data the extension handles
Cycle Calendar uses the following information you provide:
The date of your last period
Your average period duration (in days)
Your average cycle length (in days)
Your preferred language (English or Ukrainian)
Your choice of how many cycles to generate
2. Where your data is stored
Your settings are saved using Chrome's local storage (chrome.storage.local), which means they stay entirely on your device. They are never transmitted to any external server operated by us.
Calendar events are created directly in your own Google Calendar account via the official Google Calendar API. We do not have access to your Google account — the connection is made directly between your browser and Google using OAuth 2.0.
3. Google account access
When you first use the extension, you will be asked to sign in with Google. This grants the extension permission to:
Create and manage a calendar named "My Cycle" (or "Мій цикл") in your Google account
Create, update, and delete events within that calendar
This permission is scoped to https://www.googleapis.com/auth/calendar. The extension does not read any of your existing calendars or events beyond the ones it creates.
4. Data protection and security
We take the following measures to protect your data:
Local-only storage: All cycle settings are stored exclusively in chrome.storage.local on your device. This data is sandboxed to the extension and cannot be accessed by websites or other extensions.
No data transmission: Your cycle data is never sent to any server, third party, or analytics service. The only external communication is directly between your browser and Google's official API endpoints (googleapis.com).
OAuth 2.0: Authentication is handled entirely by Chrome's built-in chrome.identity API using Google's secure OAuth 2.0 flow. The extension never sees or stores your Google password or account credentials.
Minimal permissions: The extension requests only the permissions necessary to function — identity for authentication, storage for local settings, and calendar access scoped strictly to the "My Cycle" calendar.
No sensitive data transmission: Health-related information (your cycle dates) never leaves your device except to create calendar events in your own Google account, which is protected by Google's own security infrastructure.
5. Data retention and deletion
We do not store any of your data on external servers, so there is nothing for us to retain or delete on our end. Here is how data is managed across each storage location:
Local extension settings (chrome.storage.local): Retained on your device for as long as the extension is installed. Automatically deleted when you uninstall the extension. You can also clear it manually by uninstalling and reinstalling the extension.
Google Calendar events: Stored in your own Google account. Future events are automatically replaced each time you regenerate your calendar. Past events are retained for personal history and reflection. You can delete individual events or the entire "My Cycle" calendar at any time directly in Google Calendar.
Google OAuth token: Managed entirely by Chrome and Google. You can revoke the extension's access to your Google account at any time by visiting myaccount.google.com/permissions and removing Cycle Calendar.
To delete all data associated with this extension: (1) delete the "My Cycle" calendar in Google Calendar, (2) revoke access at myaccount.google.com/permissions, and (3) uninstall the extension from Chrome.
6. Data we do NOT collect
We do not collect any personal information
We do not use analytics or tracking
We do not use cookies
We do not share any data with third parties
We do not have a server or database of any kind
7. Medical disclaimer
Cycle Calendar is a personal wellness and productivity tool. It is not a medical device and does not provide medical advice. The phase dates and descriptions are estimates based on average cycle patterns and are for general informational awareness only.
Do not use this extension to make medical decisions, diagnose health conditions, or as a method of contraception. Always consult a qualified healthcare professional for medical guidance.
8. Children's privacy
This extension is not intended for use by anyone under the age of 13. We do not knowingly collect information from children.
9. Changes to this policy
If we make material changes to this privacy policy, we will update the "Last updated" date above and release a new version of the extension. Continued use of the extension after changes constitutes acceptance of the updated policy.
10. Contact
If you have any questions about this privacy policy or the extension, please contact us at: olenka.tomchuk@gmail.com