Privacy Policy

01. Introduction

Maison Dynamics Private Limited ("we", "us", or "our") respects your privacy. This Privacy Policy explains how information is handled when you download, install, or use the One Calculator mobile application on Android, iPhone and iPad.

One Calculator is built so that your numbers stay with you. There is no account, no sign-in and no analytics SDK. This policy lists everything the app keeps on your device and the few features that use the network, so that nothing here is a surprise.

02. Calculations Stay on Your Device

We do not transmit, collect, log or store your calculation expressions, tape steps or results on any server. Everything except currency refresh, purchase verification and advertising works fully offline.

03. Information Stored Locally on Your Device

One Calculator uses app-private storage on your device (Android SharedPreferences and iOS UserDefaults) to remember your work and preferences:

• Calculation tape and history: the steps of your current calculation and up to 200 saved results. AC clears the tape; History has a Clear history action.
• Preferences: appearance (light, dark or system), language (system, English or Hindi), Indian number grouping, key feedback, angle unit, the keypad mode you last used, your GST rate and supply type, and the last title you typed on a shared sheet.
• Cached currency rates: the last exchange rate you fetched, with its date, so the converter works offline and labels the rate as cached.
• Purchase entitlement: after a verified "Remove ads" purchase, a proof of purchase is kept in device secure storage (Android Keystore-backed storage, iOS Keychain) so the app stays ad-free offline. On iOS this item does not sync to iCloud Keychain and is not restored to another device; use Restore purchases instead.
• Home screen widget (Android): the widget shows your last answer, read from the app's own private storage on the device.

None of this leaves your device, and none of it is shared with or sold to anyone.

04. When the App Uses the Network

Four features make network requests. Each sends only what is listed here.

• Currency rates: the Currency tool asks Frankfurter (frankfurter.dev, publishing European Central Bank reference rates) for the rate of the currency pair you selected. The amount you typed is never sent. Like any web request, the provider receives your device's IP address.
• Purchase verification: after you buy or restore "Remove ads", the app sends the store's purchase token or receipt, the product identifier and the platform name to our verification service over HTTPS. The service confirms the purchase with Google Play or the App Store and answers yes or no. It keeps no user accounts and does not store receipts; ordinary server access logs, which contain the requesting IP address, are kept only briefly for security and are not linked to any person.
• Advertising (free edition only): described in section 05.
• Sharing a sheet: when you tap Share, the app draws an image of your calculation into its private cache folder and hands it to the app you choose, such as WhatsApp or email. We never see what you share; the app you choose handles it under its own privacy policy.

There is no other network use. The app requests no location, contacts, camera, microphone, storage or phone permissions.

05. Advertising & Third-Party Services

The free edition shows a single banner advertisement on the Tools, Study, Money and Formulas screens. There are no full-screen, launch, exit or rewarded ads, and no ads on the calculator itself.

Ads are served by Google Mobile Ads (AdMob). Before any ad is requested, Google's User Messaging Platform shows the consent options that apply in your region, and you can change them at any time under Settings → Ad privacy choices. Ad requests are made as non-personalised requests. To serve and measure ads, the SDK may process your advertising identifier, IP address and approximate location derived from it, device and app information, ad interactions and diagnostics, as described in Google's advertising policy.

• Your calculations, tape and inputs are never used as advertising inputs or shared with advertisers.
• Declining optional consent does not limit the calculator in any way.
• After a verified Remove ads purchase the advertising SDK is not initialised and no ad requests are made.

06. In-App Purchase & Payment Security

The only purchase is Remove ads, a one-time, non-consumable item. There are no subscriptions. It is processed exclusively by Google Play Billing on Android and Apple In-App Purchase on iOS, under their privacy policies.

Maison Dynamics Private Limited never receives your card, bank, UPI or store credentials. A purchase applies to the store where it was made; restore it on other devices signed in to the same store account. A refunded or revoked purchase stops providing ad-free access after the next verification or restore.

07. Children's Privacy

One Calculator is a general-audience utility for students, professionals and everyday use. It is not directed to children under 13, and we do not knowingly collect personal information from children. A parent or guardian who believes a child has provided information through our support address can ask us to delete it.

08. Your Choices & Rights

Because your data stays on your device, you control it directly:

• AC clears the current tape; History → Clear history removes saved results.
• Settings → Ad privacy choices reopens the consent options.
• Uninstalling the app deletes all locally stored history, preferences and cached data.
• Write to us to access or delete anything you have sent to support. We honour requests under applicable law, including India's Digital Personal Data Protection Act, 2023.

09. Summary of Data Collection

This matches the declarations we make in the Google Play Data safety and Apple App Privacy sections:

• Collected only in the free edition, by the advertising SDK, for advertising and analytics: advertising identifier, approximate location from IP address, app interactions, crash and diagnostic data. Shared with Google for that purpose.
• Collected for app functionality: purchase proof, processed by our verification service and stored on your device. Not shared.
• Not collected: name, email, contacts, precise location, photos, files, calculation content, or any account information. We do not sell data and do not use it for tracking across apps or websites.

10. Changes to this Privacy Policy

We may update this policy when the app or the law changes. The version number and effective date above identify the current text, which is always available at this URL and from Settings → Privacy policy inside the app.