CloudEx Inc. ("we", "us", or "our") operates the "Lock Screen Flashcards Pro" app (the "Service"). This Privacy Policy explains what information we collect, how we use it, and the choices available to you. By using the Service, you are deemed to have agreed to the practices described in this Policy.
1. Our Core Principle
Lock Screen Flashcards Pro is a flashcard app that shows you one card each time you turn on your screen (or when you unlock your phone), so you can learn in spare moments. It uses spaced repetition (a method based on SM-2) to bring each card back just as you are about to forget it. The card is shown on top of your lock screen: it does not unlock your phone and does not replace your lock screen, and closing it takes you back to your lock screen. Your decks, cards, study history, and settings are stored only on your device, and we never view, collect, upload, or transmit them to our servers. There is no account and no sign-in. Specifically, we do not have access to any of the following:
- The decks and cards you create or import, and what is written on them
- Your study history (your answers and review schedule)
- The backup and CSV files you export or import, and the text you paste into the app
- The contents of your screen or of other apps
Your decks and cards leave your device only through actions you take yourself, such as exporting a backup or a CSV file to a location you choose (Section 2).
2. Information We Collect and Do Not Collect
2.1 Information Collected Automatically
- Anonymous crash reports: Via Firebase Crashlytics. When the app crashes, we collect the device model, OS version, app version, a record of what the app was doing at the moment of the crash, and an identifier for each installation. The app does not add your decks, cards, or study history to these reports.
- Purchase information: We use purchase tokens issued by Google Play to verify your one-time "Premium" purchase. We never receive any payment information such as credit card numbers.
- List of our other apps: To show our other apps, the app downloads a list of them (a static file) from our content server hosted on Cloudflare Pages. The request contains no personal data from the app. As with any request to a web server, the server receives your device's IP address as part of the connection.
2.2 Information Stored Only on Your Device
- Decks, cards, and study history: Stored in the app's own storage on your device. They are never sent to us.
- App settings: When and how screen cards are shown, the interval, the daily limit, quiet hours, and similar settings are stored on your device.
- Automatic backups: Once a day, the app saves a backup in its own storage on your device and keeps the 7 most recent ones. They are not sent anywhere.
- Export and import: Only when you choose to, the app writes a backup (JSON) or a CSV file to the location you pick. When you restore a backup or import cards from a CSV file or pasted text, the app reads only the file you choose or the text you paste.
- Read aloud: Uses the text-to-speech (TTS) engine installed on your device. The text of the card is passed only to that engine; we do not receive it. How the engine handles the text depends on its provider.
- "Not during calls": To tell whether you are on a call, the app looks only at your device's audio mode. It does not use your phone number, your call log, or the phone-state permission.
- Android backup: If backup is turned on in your device settings, Android may include the app's decks, cards, study history, and settings in your device backup to your Google account, and restore them on a new phone. This backup is handled by Google under your account; we cannot access it. The app's automatic backups are excluded from it. You can turn device backup off in your device settings.
- When you uninstall: Uninstalling the app or clearing its data deletes the decks, cards, study history, settings, and automatic backups stored in the app's own storage. Files you exported to a location you chose remain until you delete them.
2.3 Information We Explicitly Do Not Collect
- Your decks, cards, and study history, or the files you export or import
- Your name, email address, or phone number (the app has no account or sign-in)
- Your contacts, call log, or phone-state information
- Your location, or anything from the camera or microphone (the app does not use them)
- The contents of your screen or of other apps (the app does not use an accessibility service)
- Your device's advertising ID (the app does not request the advertising ID permission)
3. Permissions the App Requests and Their Purposes
Lock Screen Flashcards Pro uses the following OS permissions only for the stated purposes:
- Display over other apps (SYSTEM_ALERT_WINDOW) — Used only with the display style "Big card on screen", to open the card screen when you turn on your screen. On Android 10 and later, only apps with this permission can open a screen from the background. The app does not show a floating window, and it does not read any screen content. It is not needed if you choose "As a notification".
- Notifications (POST_NOTIFICATIONS, Android 13+) — Shows the ongoing notification with the pause, "Resume", and "Show one now" buttons, study reminders, and the card itself when you choose "As a notification".
- Foreground service (FOREGROUND_SERVICE / FOREGROUND_SERVICE_SPECIAL_USE) — Runs only while screen cards are on, so that the app can tell when your screen has been turned on.
- Run at startup (RECEIVE_BOOT_COMPLETED) — Resumes screen cards after your phone restarts.
- Internet and network status (INTERNET / ACCESS_NETWORK_STATE) — Used only for anonymous crash reports, Google Play purchase verification, in-app reviews and in-app updates, downloading the list of our other apps, and showing this privacy policy in the app. Screen cards, studying, and your decks work without an internet connection.
- Google Play billing (com.android.vending.BILLING) — Used to purchase Premium.
The app does not request permissions for location, the camera, the microphone, contacts, or the phone, and it does not use an accessibility service.
4. How We Use Information
The limited information we collect is used only for the following purposes:
- Operating and maintaining the Service
- Verifying your Premium purchase
- Diagnosing and fixing crashes
- Showing the list of our other apps in the app
- Responding to support inquiries
- Complying with applicable laws
5. Third-Party Services
Lock Screen Flashcards Pro uses the following third-party services. Each service has its own privacy policy.
- Firebase Crashlytics (Google LLC) — anonymous crash diagnostic data
- Google Play Billing (Google LLC) — the one-time Premium purchase; payment is completed on Google Play, and we receive only a purchase token
- Google Play In-App Review and In-App Updates (Google LLC) — let you rate the app and install updates without leaving it; handled by Google Play
- Cloudflare Pages (Cloudflare, Inc.) — hosts the static list of our other apps
Lock Screen Flashcards Pro does not use advertising SDKs or the advertising ID, and does not share your data with advertising networks.
6. Data Retention
- Crash reports: retained for 90 days, then deleted.
- Support emails: retained for 12 months after the last reply, then deleted (except where legally required).
- Your decks, cards, study history, and settings on your device: kept until you delete them, uninstall the app, or clear the app's data. Only the 7 most recent automatic backups are kept; older ones are deleted automatically.
7. International Data Transfers
We are based in Japan. The infrastructure used for crash diagnostics, purchase verification, and hosting the list of our other apps may be located in various countries. When you use the Service, the minimal information described above may be processed outside your country of residence under standard contractual safeguards.
8. Your Rights
Depending on where you reside (e.g., the EEA, UK, California, Japan), you may have the right to request access to, correction of, or deletion of the limited information we hold. You can:
- Delete decks and cards in the app at any time, or uninstall the app or clear its data to erase everything it stores on your device
- Turn screen cards off or pause them at any time
- Withdraw the notification or "Display over other apps" permission in your device settings at any time
- Contact us at the address below to make a request regarding the information we hold
9. Children's Privacy
Lock Screen Flashcards Pro is not directed to children under the age of 13 (or the minimum age applicable in your region). If we inadvertently collect information from such a child, we will delete it promptly upon being contacted.
10. Changes to This Policy
This Privacy Policy may be updated from time to time. The latest version is always published at this URL together with its effective date. We will also notify you within the app of significant changes as appropriate.
11. Contact
For questions about privacy, data requests, or to report concerns, please email us at .
CloudEx Inc. (Japan)
Effective Date: October 28, 2026