Privacy Policy

Effective date: September 18, 2026 · Developer: Phong Nguyen Xuan · Contact: storevn.feedback@gmail.com · Application: Calculator for iOS

1. Introduction

Calculator ("the app", "we", "us") is a multi-function calculator that includes a standard/scientific calculator and a set of converter tools (unit, currency, date/time, health, finance, and more). This Privacy Policy explains what data we process, why, and the choices available to you.

Core principle: everything you enter is processed and stored locally on your device. We do not sell your personal data, we do not run advertising, and we do not use analytics.

2. Data processed and stored locally on your device (never uploaded)

• Calculation history and tool results (calculator, percentage, discount, tip, loan, savings, GPA, and others)
• Personalization settings: language, theme, background, number format, measurement units
• Custom backgrounds: when you choose an image through the iOS photo picker, the image is cropped and stored in the app's private storage; it is not uploaded or shared
• Ovulation / Menstrual Cycle data: the cycle dates, notes and reminder settings you enter are stored locally to perform calculations and schedule on-device notifications. This data never leaves your device and is not sent to us or any third party

You can delete this data by removing individual entries within the app, or by deleting the app.

Device backup: if you have iCloud Backup enabled in iOS Settings, your device backup may include the app's data, in the same way it includes data from your other apps. That backup is created and encrypted by Apple; the app itself never transmits your data anywhere. You control it in iOS Settings → [your name] → iCloud → iCloud Backup.

3. Data collected through third-party services

The app uses exactly one third-party service:

Firebase Remote Config (Google) — fetches a small remote configuration value that controls the colour of tool cards in the interface. To do this, the Firebase SDK creates a Firebase Installation ID (FID): a pseudonymous identifier stored on your device. The FID is not linked to your identity, is not used to track you across apps or websites, and is not used for advertising. It exists solely so the configuration service can deliver a consistent configuration to your installation. The SDK may also report basic diagnostic information about its own operation.

Data processed by Google is handled in accordance with Google's Privacy Policy: https://policies.google.com/privacy

The app does NOT use analytics, crash reporting, advertising SDKs, or an advertising identifier.

4. Permissions

• Notifications — used only to send reminders for the Ovulation / Menstrual Cycle tool, and only if you turn reminders on. You can revoke this at any time in iOS Settings → Notifications.
• Photos — the app uses the standard iOS photo picker so you can choose an image as a background. The picker runs outside the app; the app receives only the single image you select and never gains access to your photo library.

The app requests no other permissions. It does not use location, contacts, microphone, camera, or health data from HealthKit.

5. Sensitive data (health)

The Ovulation / Menstrual Cycle tool processes reproductive-health-related information (cycle dates and optional notes). This information is stored only on your device and is used for on-device calculations and reminders. We do not collect, transmit, or share it.

This tool provides estimates for reference only. It is not a medical device and should not be used as a contraception method or as a substitute for professional medical advice.

6. Data sharing

We do not sell personal data and we do not share your calculation data with anyone. The app makes only two kinds of network requests: the Firebase Remote Config request described in Section 3, and the exchange-rate request described in Section 7. Neither contains your calculations, amounts, notes, or any other content you enter.

7. Exchange rates

The Currency Converter downloads current exchange rates from ExchangeRate-API (open.er-api.com), a third-party service. The request is made when you open or refresh the Currency Converter and the rates stored on your device are out of date. It contains only a currency code (for example "USD"). It does not contain the amounts you convert, your conversion history, any identifier created by the app, or any account information, and the app uses no cookies for this request. As with any internet request, the service necessarily receives your device's IP address and standard technical request information. ExchangeRate-API's privacy policy is available at https://www.exchangerate-api.com/privacy.

Downloaded rates are stored on your device so the converter keeps working offline. Rates are shown together with the date they were last updated and the required attribution ("Rates By Exchange Rate API"). If the request fails, the app continues to use the most recent rates it has.

8. Children's privacy

The app is rated 4+ and is not directed at children under 13. We do not knowingly collect personal information from children.

9. Changes to this policy

If we change what data the app processes, we will update this page and change the effective date above.

10. Contact

Questions or requests: storevn.feedback@gmail.com

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