NightCurve ("we", "us", "our", "the app") is a blood alcohol content (BAC) estimation tool developed by an independent developer based in Poland. For the purposes of the EU General Data Protection Regulation (GDPR), the UK GDPR, and the Polish Act on the Protection of Personal Data (RODO), we act as the data controller for any personal data processed through the app.
This Privacy Policy explains how we collect, use, and protect your information. It applies to the NightCurve iOS app, the Apple Watch companion app, Live Activities (Lock Screen widgets), and all associated features.
2. Data We Process On Your Device
NightCurve stores ALL data exclusively and locally on your device. We do NOT collect, transmit, or store any personal data on external servers.
Depending on how you use the app, the following data may be stored locally on your device:
Profile information (weight, age, biological sex) — used solely for BAC calculations based on the Widmark formula
Drink records (type, volume, alcohol percentage, timestamp, alcohol color, mixer type) — used for BAC estimation, statistics, and hangover risk assessment
Drinking session data (water intake, meal status, meal size, session timestamps) — used for hangover risk calculation
App preferences (region, unit system, language, visual effects) — used to customize the user experience
Premium access status — managed through Apple's StoreKit framework
3. Health and Sensitive Data
Information about alcohol consumption, drinking behavior, and estimated blood alcohol content (BAC) may be considered sensitive or health-related data in some jurisdictions, including under the GDPR (Article 9), UK GDPR, and similar regulations.
NightCurve processes this information exclusively on your device to provide BAC estimation, session tracking, statistics, Apple Watch sync, Live Activities, and related features. We do not transmit this data to our own servers, advertisers, analytics providers, or other third parties.
4. Data We Do Not Collect
We do NOT collect:
Your name, phone number, or contact information through the app itself
Location or geolocation data
Device identifiers, advertising identifiers, or fingerprinting data
Usage analytics, behavioral data, or telemetry
Health data from Apple HealthKit
Crash reports or diagnostic data sent to the developer
Cookies or similar tracking technologies
Biometric data
Any data transmitted to external servers
If you contact us directly by email, we will process the contact information and message content you choose to provide solely for support, legal, or customer-service correspondence.
5. Lawful Basis for Processing (GDPR Article 6)
We process your personal data on the following lawful bases:
Consent (Article 6(1)(a)): You voluntarily enter your data to use the app's core functionality.
Legitimate interest (Article 6(1)(f)): Processing is necessary to provide and maintain the app features you choose to use on your own device.
Where alcohol-related and BAC estimation data is treated as health-related data under applicable law, we rely on your voluntary and affirmative provision and use of that data solely to provide the features you request within the app.
You may withdraw your consent at any time by deleting your data within the app or by uninstalling the app entirely.
6. Purpose of Processing
Your data is processed exclusively for the following purposes:
BAC estimation using the Widmark formula (weight, age, biological sex)
Displaying real-time BAC status via Live Activities on your Lock Screen
Syncing session data with the Apple Watch companion app
Verifying premium feature access via Apple StoreKit
We do NOT use your data for profiling, marketing, advertising, or any purpose beyond the stated functionality.
7. Apple Watch Companion
If you use the Apple Watch companion app, drink data and BAC status are transferred between your iPhone and Apple Watch using Apple's WatchConnectivity framework. This communication occurs directly between your paired devices over Bluetooth and does not pass through any external servers. Data stored on the Apple Watch is kept locally on the watch.
8. Live Activities (Lock Screen)
NightCurve uses Apple's ActivityKit to display BAC status, time to sobriety, and status text on your Lock Screen and Dynamic Island. This data is processed and displayed entirely on your device using Apple's system frameworks. No data is transmitted externally.
9. In-App Purchases
Premium purchases are processed entirely by Apple through the App Store using StoreKit. We do not have access to your payment information, Apple ID, or billing details. For information about how Apple handles your payment data, please refer to Apple's Privacy Policy: apple.com/legal/privacy
10. Third-Party Services
NightCurve does not integrate any third-party analytics, advertising, crash reporting, or tracking services. We do not share, sell, rent, or otherwise disclose your data to any third parties.
The only external service interaction is with Apple's StoreKit for in-app purchase verification, which is handled entirely by Apple's infrastructure.
11. Data Storage, Security, and Retention
Storage: All data is stored locally on your device using Apple's SwiftData framework (an on-device database).
Apple Watch: If you use the companion watch app, a limited copy of relevant session state may also be stored locally on your paired Apple Watch.
No cloud sync: Data is not synced to iCloud, CloudKit, or any cloud service.
Security: Data is protected by your device's built-in security features, including device encryption, passcode, Face ID, and Touch ID.
Retention: Data is retained on your device for as long as the app is installed. You may delete individual drink records, reset all data from Settings, or uninstall the app to permanently remove all data.
Deletion: When you uninstall the app, locally stored app data is removed from that device. If you also use the Apple Watch companion app, data stored on the watch is removed when the watch app is removed.
12. International Data Transfers
Since all personal data is stored exclusively on your device and is never transmitted to external servers, no international or cross-border data transfers occur. This applies regardless of your location.
For in-app purchases, Apple may process transaction data in jurisdictions where Apple operates. Please refer to Apple's Privacy Policy for details.
13. Your Rights
Depending on your jurisdiction, you have the following rights regarding your personal data:
EU/EEA, UK, and Poland (GDPR / UK GDPR / RODO)
Right of access (Art. 15) — view your data directly in the app
Right to rectification (Art. 16) — edit your profile and drink records at any time
Right to erasure (Art. 17) — delete individual records, reset all data, or uninstall the app
Right to restrict processing (Art. 18)
Right to data portability (Art. 20) — your data is already stored locally on your device
Right to object (Art. 21)
Right to withdraw consent at any time (Art. 7(3)) — without affecting the lawfulness of processing based on consent before its withdrawal
Right to lodge a complaint with a supervisory authority:
Poland: Prezes Urzędu Ochrony Danych Osobowych (PUODO), uodo.gov.pl
UK: Information Commissioner's Office (ICO), ico.org.uk
EU: Your local Data Protection Authority
California, USA (CCPA/CPRA)
Right to know what personal information is collected
Right to delete personal information
Right to opt-out of sale or sharing of personal information — we do NOT sell or share your personal information
Right to non-discrimination for exercising your rights
We do NOT sell your personal data. We do NOT share your personal data for cross-context behavioral advertising.
China (PIPL)
Right to know and decide on the processing of your personal information
Right to restrict or refuse processing
Right to access and copy your personal information
Right to correct and supplement your information
Right to request deletion
Right to request explanation of processing rules
Right to withdraw consent
No cross-border transfer of personal information occurs.
Australia (Privacy Act 1988 / APPs)
Right to access your personal information (APP 12)
Right to correction of personal information (APP 13)
Right to anonymity or pseudonymity where practicable (APP 2)
Right to complain to the Office of the Australian Information Commissioner (OAIC), oaic.gov.au
Since all data is stored locally on your device, you exercise most of these rights directly by editing or deleting data within the app, or by uninstalling the app. For any requests you cannot fulfill directly, contact us at alcotrack.app@gmail.com.
14. Children's Privacy
NightCurve is not intended for use by anyone under the legal drinking age in their jurisdiction (21 in the USA, 18 in most other countries). The app is rated 17+ on the Apple App Store due to alcohol-related content.
We do not knowingly collect personal information from children under 13 (COPPA, USA), under 16 (GDPR, EU), under 14 (PIPL, China), or under the legal drinking age in any jurisdiction. If we become aware that a minor has used the app, we encourage the parent or guardian to contact us so we can assist with data deletion.
15. Data Breach Notification
Since all core user data is stored exclusively on your device and we do not have direct access to it, the risk of a server-side personal data breach by us is limited. If we become aware of a security incident affecting the app, its components, or our legal obligations toward users, we will assess and fulfill any notification duties required by applicable law.
16. Changes to This Policy
We may update this Privacy Policy from time to time. Any changes will be reflected in the app with an updated "Last updated" date. We encourage you to review this policy periodically. Continued use of the app after changes constitutes acceptance of the updated policy.
17. Contact
If you have any questions about this Privacy Policy, wish to exercise your rights, or have concerns about your data, please contact us:
For EU users, you may also file a complaint with your local Data Protection Authority or use the EU Online Dispute Resolution platform: ec.europa.eu/consumers/odr