Lucid Sudoku — Privacy Policy
Effective date: 2026-06-04
Last updated: 2026-06-04
Lucid Sudoku (“the app”) is built and operated by an independent developer (“we”, “us”). This policy explains what data the app collects, why, and how you control it. It applies to the Lucid Sudoku iOS app distributed through the Apple App Store.
Summary (the short version)
- No account. No login. No email collected.
- No ads. No third-party advertising SDKs. No tracking across apps or websites.
- No puzzle content, no photos, no contacts, no precise location ever leaves your device.
- We collect anonymous crash reports and anonymous usage analytics via Google Firebase Crashlytics and Firebase Analytics, to fix bugs and understand which lessons help people learn.
- All collection is not linked to your identity and not used for tracking (per Apple’s definitions).
- You can turn it all off with a single toggle: Settings → Privacy inside the app.
What we collect
1. Crash diagnostics (Firebase Crashlytics)
When the app crashes, an automated crash report is sent containing:
- Stack trace and crash type
- iOS version, device model, app version, locale
- An app-instance device identifier (a random ID generated for this install — not your Apple ID, not your IDFA, not your phone number)
Purpose: fix bugs.
2. Anonymous product analytics (Firebase Analytics)
The app records anonymous, aggregated events such as:
- Which technique lessons you start and complete
- Bucketed durations (e.g. “30–60 seconds”) — not exact timestamps
- OS-major bucket (e.g. “iOS 18”) — not the full version string
- An app-instance device identifier (same as above)
Purpose: understand which lessons help people learn and which need rework.
We do not collect:
- Your name, email, phone number, address, or any contact info
- Apple ID, iCloud account info, or any sign-in identifier
- IDFA (the advertising identifier) — we do not request it and do not show ATT prompts
- Precise or approximate location
- Puzzle content (the actual numbers in any puzzle you play or enter)
- Photos, microphone, camera, contacts, calendar, or health data
- Browsing history or data from other apps
3. Purchase data (Apple)
When you buy the full unlock, the transaction is handled entirely by Apple’s StoreKit. We receive only a receipt that confirms the purchase is valid. Your payment details never touch our systems.
How you control it
- Opt-out toggle: Open the app → Settings → Privacy → turn off “Anonymous Analytics & Crash Reports”. This disables both Firebase Analytics and Crashlytics together, immediately.
- Reset analytics ID: Reinstalling the app generates a new app-instance identifier with no link to the previous one.
- Delete your data: Because no data is linked to your identity, we cannot look up “your” records. Uninstalling the app stops all future collection. Past anonymous records expire on Firebase’s standard retention schedule.
Apple’s “App Privacy” nutrition label
For reference, the App Store listing declares:
| Data Type |
Category |
Linked to you |
Used for tracking |
Purpose |
| Crash Data |
Diagnostics |
No |
No |
App Functionality |
| Product Interaction |
Usage Data |
No |
No |
Analytics |
| Other Usage Data |
Usage Data |
No |
No |
Analytics |
| Device ID (app-instance) |
Identifiers |
No |
No |
Analytics |
“Used for tracking” overall: No.
Third parties
We do not share data with anyone else. No data brokers. No ad networks.
Children
The app is appropriate for all ages and does not knowingly collect any personal information from children. There is no account system, no chat, no user-generated content shared between users.
Changes to this policy
If we make material changes, we will update the “Last updated” date above and, where appropriate, surface a notice in the app. Continued use after a change indicates acceptance.
Questions, requests, or concerns:
trungnguyen.1791@gmail.com
For app help, see the Support page.