Last updated: August 30, 2026
This Privacy Policy explains how the mobile application Twin Calc ("the App"), provided by Hiroki Sugiyama ("we", "us"), handles your information. The App is an iOS application that shows two independent calculators on one screen.
The App does not collect personal information such as your name or email address. There is no account system and no backend server operated by us. Everything you calculate stays on your device. To improve the App, we collect only the anonymous usage data described in "Usage Analytics" below.
The numbers you enter, the results, and the calculation history ("tape") are stored only on your device so that the App can restore them when you reopen it. They are never uploaded to any server and are never shared with us or any third party.
Purchases (the one-time PRO upgrade) are processed by Apple through the App Store. To verify and manage your purchase status, the App uses a purchase-management service (RevenueCat), which processes an anonymous identifier and basic purchase/device information. We do not receive your name, email address, or payment card details.
To improve the App, we use an analytics service (PostHog) to collect anonymous usage data: events such as screen views and button interactions, along with basic information like OS version, device model, and app version. This data is tied only to an anonymous identifier and is never linked to personal information such as your name or email address. The numbers you enter and your results are never transmitted. We use this data solely to analyze and improve the App; it is not used for advertising and is never sold or shared with third parties.
The App does not show ads and does not perform any advertising-related tracking.
All App data (calculator state, history, and settings) remains on your device. You can clear the history within the App at any time. Deleting the App from your device removes all of this data.
The App is not directed to children under the age of 13 and does not knowingly collect personal information from children.
We may update this Privacy Policy from time to time. The latest version will always be available at this page, with the "Last updated" date revised accordingly.
If you have any questions about this Privacy Policy, contact us at hiroki.sugiyama.dev@gmail.com.