Privacy Policy for LightnFast

Effective date: September 7, 2026
Developer: Shanhe Yi
Contact: ysh@yishanhe.net

LightnFast is an intermittent fasting tracker built around local data ownership. It has no LightnFast account, advertising, or third-party analytics and does not operate a remote application server.

1. Data stored on your iPhone

Fasting plans, fasting history, daily goals, bedtime entries, notes, and related app state are stored on your iPhone. If you enable iCloud sync, app records also sync through your private iCloud account as described below.

The developer does not operate a server containing your app records. Local model and widget snapshot directories are marked for exclusion from device backups. If iCloud sync is off or a record has not synced, deleting the app, losing the iPhone, or replacing it can permanently lose that record. Sync is not a separate historical backup. You can create CSV exports from Settings > Data > Export data; LightnFast cannot import them. A destination you choose when sharing an export receives that copy and controls its handling.

2. Apple Health

Apple Health access is optional and controlled by the permissions you grant in iOS.

• LightnFast may read supported weight, body composition, and sleep data to display trends or prefill entries.
• LightnFast may write supported weight and water entries when you explicitly log or enable them.
• LightnFast does not write fasting sessions to Apple Health.
• Weight and body-composition reads are used on device and are not copied into LightnFast’s iCloud records.
• A sleep reading may suggest a bedtime in a form. If you save that suggested bedtime, it becomes part of your daily record and can sync through iCloud when record sync is enabled.
• LightnFast does not send Health readings to a developer-operated server.

You can review or revoke access in the Health app or iOS Settings.

3. Optional iCloud record sync and preferences

If you choose Turn on sync, LightnFast uses Apple’s CloudKit service to sync fasting plans, fasts, goals, daily results, saved bedtime entries, and notes through your private iCloud account. The choice takes effect the next time the app opens. Sync depends on your Apple Account, connectivity, and Apple’s services; it is not an immediate or guaranteed backup.

Separately, five notification preferences can sync using Apple’s iCloud key-value storage. These preferences can survive an app reinstall. LightnFast does not provide an in-app reset for that preference store. Turning off record sync does not delete records already stored in iCloud.

4. Purchases

Pro is available through monthly or yearly auto-renewable subscriptions processed by Apple through StoreKit. LightnFast does not receive or store your payment-card details. Apple may process purchase data under its own privacy policy. You can restore purchases and manage your subscription through Apple’s account controls.

5. Notifications and widgets

If you enable notifications, LightnFast schedules them using Apple’s system services. Widgets and Live Activities may display fasting status you choose to make visible on supported system surfaces.

The paired Apple Watch companion exchanges current fasting status and start/end commands with your iPhone through Apple’s WatchConnectivity framework. The Watch app and complications display this status; purchases are managed on iPhone.

6. No tracking or sale of data

LightnFast does not use third-party advertising or analytics SDKs, track you across apps or websites, or sell your personal data.

7. Data deletion

You can delete fasts and clear daily entries in the app. Removing a goal archives it and preserves its history. With iCloud record sync enabled, record changes and deletions can sync to your other devices. Deleting the app does not itself delete records already in iCloud or the synced notification preferences. You can manage app iCloud storage through Apple’s account and device settings. Data already written to Apple Health can be managed in Apple Health. Exports you saved or shared remain at their chosen destinations.

8. Children’s privacy

LightnFast is not directed to children under 13, and the developer does not knowingly collect personal information from children.

9. Changes

Material changes to this policy will be posted here with a revised effective date.

10. Contact

Questions about this policy can be sent to ysh@yishanhe.net.