App: MathDeck (io.github.omniverse_lab.mathdeck)
Publisher: Omniverse Labs
Contact: visualtales8@gmail.com
Effective date: 2026-04-16
Last updated: 2026-06-03
This Privacy Policy describes how the MathDeck Android application ("MathDeck", "the app", "we", "us", "our") handles information on your device. By using MathDeck you agree to the practices described here.
Plain-English summary: MathDeck is a calculator and a simple to-do list. It does not collect, upload, or sell your personal data - your tasks and history stay on your device. The only network request it makes is to a public currency exchange-rate service, and only if you open the Currency Converter screen.
Information We Collect
MathDeck does not collect, transmit, or store any personally identifiable information (PII) on any server controlled by us. MathDeck does not create user accounts, profiles, or log-ins.
The only data the app handles is created by you, stays on your device, and is used purely to deliver in-app functionality.
Calculation history: your past calculations (inputs, results, calculator mode, timestamp), kept in a local Room database so you can view, filter, and delete them in the History screen.
To-do tasks: tasks you create in Tasks mode (title, done state, due-day bucket, per-task stopwatch time), kept in a local Room database to power the Tasks list and its timer.
App preferences: theme (light/dark), haptic and sound toggles, selected profile (Pro / Simple / Custom), and visible calculator modes, kept in local DataStore / SharedPreferences.
Cached currency rates: the last fetched USD-base exchange rates and the fetch timestamp, kept in local SharedPreferences so the Currency Converter works offline after one refresh.
You can remove all of this data at any time: delete individual entries from the in-app History screen, use Android Settings > Apps > MathDeck > Storage > Clear storage / Clear data, or uninstall the app.
Information We Do Not Collect
We do not collect, and the app does not send, any of the following: your name, email address, phone number, or postal address; contacts, calendar, call logs, or SMS; photos, videos, or any media from your device; precise or approximate location; microphone or camera input; device identifiers (Advertising ID, IMEI, MAC address, serial); account credentials or passwords; biometrics or health data (BMI and body metrics in the Health calculator are computed locally and are not transmitted); financial inputs (EMI, interest, and ROI calculations stay on-device); or any form of analytics, telemetry, or crash-report payload.
There are no third-party SDKs for analytics, advertising, attribution, or crash reporting bundled into MathDeck.
Network Access
MathDeck requests the Android INTERNET permission for one purpose only: fetching public currency exchange rates.
Endpoint: https://open.er-api.com/v6/latest/USD
Provider: Open Exchange Rates Open API (er-api.com), a free, unauthenticated public endpoint.
When the call happens: only when you open the Currency Converter screen and trigger a refresh.
What is sent: nothing from you. No query parameters, cookies, headers, or identifiers are attached - a standard HTTPS TLS connection only.
What is received: a JSON object of USD-based exchange rates.
Logging on our side: none. We operate no backend.
If you never open the Currency Converter, MathDeck makes zero outbound network requests. No request from MathDeck contains any user-generated content (calculator inputs, history entries, settings, etc.).
Permissions
MathDeck requests a single permission - android.permission.INTERNET - used only to fetch public currency exchange rates for the Currency Converter screen. MathDeck does not request any of the runtime "dangerous" permissions (location, camera, microphone, contacts, storage outside its sandbox, SMS, phone, calendar, etc.).
Children's Privacy
MathDeck is suitable for general audiences, including users under 13. Because the app does not collect personal information from any user, it also does not knowingly collect personal information from children. We comply with the U.S. Children's Online Privacy Protection Act (COPPA) and Google Play's Families policy.
If a parent or guardian believes their child has somehow provided us with personal information, please contact us and we will delete any records (noting that, by design, we do not hold any).
Data Security
Because MathDeck stores all user data locally on the device, its security is governed by Android's application sandbox. Per-app private storage is isolated from other apps. Network traffic for the one external endpoint is sent over HTTPS (TLS 1.2+). Release builds are compiled with R8 code shrinking and obfuscation, signed with a production keystore, and have debug logging stripped so no verbose log lines survive into production.
We do not hold any personal data on a server, so there is no server-side breach risk attributable to us.
Third-Party Services
The only external service MathDeck contacts is open.er-api.com (the Open Exchange Rates Open API), which returns public USD-based exchange rates. No data is shared from you - only a standard anonymous HTTPS request. We do not integrate with advertising networks, analytics providers, crash reporters, A/B testing services, attribution SDKs, social-login providers, or any similar third-party services.
Data Retention and Deletion
On-device data (history, settings, cached rates) persists until you delete it via the in-app controls, clear the app's storage from Android Settings, or uninstall the app. Uninstalling MathDeck removes all data the app has stored. Because we do not operate a backend, there is no server-side retention and no deletion request to make.
Your Rights
Because MathDeck does not collect personal data, privacy-law "data subject" rights under GDPR, CCPA, and similar regimes (access, rectification, erasure, portability) apply only to on-device data, which is already under your direct control through the Android operating system and the in-app History and Settings screens. If you have any questions or concerns about your rights, email us at visualtales8@gmail.com.
Changes to This Policy
We may update this policy from time to time. The "Last updated" date at the top reflects the most recent revision. If we make material changes (for example, adding a new network service or analytics SDK), we will update the policy and bump the app's version. Continued use of MathDeck after an update means you accept the revised policy.
Contact
For any questions or concerns about this policy:
Email: visualtales8@gmail.com
Publisher: Omniverse Labs
App listing: https://play.google.com/store/apps/details?id=io.github.omniverse_lab.mathdeck
Google Play Data Safety Summary
This app's Data Safety declaration on Google Play is: it does not collect or share any of the required user data types; the only data it handles stays on your device; all network traffic (the single exchange-rate request) is encrypted in transit over HTTPS; and you can request deletion of your data by clearing it in-app or uninstalling, since no server-side data exists.