Jet Lag Engine — Privacy Policy
Effective date: July 17, 2026
This privacy policy applies to the Jet Lag Engine app for iPhone (the “Application”), created by Dennis van Dalen (the “Service Provider”). The Application is provided as-is.
The short version
Jet Lag Engine works without an account, advertising, analytics, tracking, or a developer-operated backend. The Service Provider does not collect, receive, sell, or share your itinerary, sleep information, behavior logs, or generated plan through the Application.
Data stored on your device
The Application stores the information required to provide its features locally. This may include:
- your itinerary, airports, ordered layovers, and travel times;
- your usual sleep schedule and optional recent sleep and wake records;
- coffee and melatonin times you choose to log;
- plan settings, generated recommendations, and algorithm provenance;
- notification preferences and optional trip history; and
- a compact active-plan snapshot used by widgets and Live Activities.
This information is stored in the Application’s local container and private App Group container on your device. It is not transmitted to the Service Provider.
Coffee logs are used only to show whether an intake occurred after a planned caffeine cutoff. Melatonin entries are record-only: they do not change the plan, infer a physiological response, or generate dosage advice.
Notifications, widgets, and Live Activities
If you opt in, iOS delivers local notifications derived from plan timestamps. Small and medium widgets and the travel-window Live Activity read a compact active-plan snapshot from the Application’s private App Group container.
These system features operate on your device. The Application does not use remote push notifications, transmit your itinerary to a server, or give the Service Provider notification-interaction data.
Exports
The Application lets you share a text summary or JSON plan export. Exporting is initiated by you, and you choose the destination through features provided by iOS.
Once you share information outside the Application, its handling depends on the application, service, location, or person you selected. The Service Provider cannot access or control those copies.
Airport and daylight data
Airport search uses a bundled index derived from the MIT-licensed airportsdata project. Timezone handling, plan generation, and daylight feasibility calculations happen on the device. Airport searches do not leave your phone.
Backups and Apple services
Depending on your device and backup settings, Apple may include locally stored Application data in an iPhone or iCloud backup. Apple may also independently process information related to downloading the Application, App Store purchases, crash reports, or device diagnostics under Apple’s privacy terms and your settings.
The Service Provider does not operate or have access to a synchronized trip database.
Retention and deletion
Your information remains in the Application until you delete the active trip, delete history items, use Delete all data, or remove the Application. Deleting the Application removes its local containers from that device, subject to backups controlled by Apple and your settings.
Previously exported copies must be deleted separately wherever you saved or shared them. Because the Service Provider does not receive Application data, there is no server-side account or trip record for the Service Provider to retrieve or delete.
Wellness information
Jet Lag Engine provides general educational travel guidance. It estimates body-clock timing from sleep information you enter. It does not measure biological phase, diagnose a condition, provide medical treatment, guarantee alertness or recovery, or recommend a supplement dose.
Children’s privacy
The Application is a general travel utility and is not directed at children under 13. The Service Provider does not knowingly collect personal information from children through the Application.
Security
Keeping information on your device limits how it is exposed to the Service Provider, but no device or storage method is completely secure. You are responsible for protecting access to your device and any files you export.
Changes and contact
This policy may change if the Application’s features or data practices change. The latest version will remain on this page with an updated effective date.
For privacy questions or help with the Application, visit Jet Lag Engine support.