Legal · Privacy
Privacy Policy
Stack is local-first by design. Your training data stays on your device unless you choose features that move it elsewhere.
This Privacy Policy explains how Lauterstar handles information for Stack - Gym Tracker ("Stack", "we", "us", or "our"). Stack does not have social features, public profiles, advertising, or our own workout-data servers.
Information You Store in Stack
Stack lets you record workouts, exercises, sets, reps, weights, routines, training goals, notes, theme choices, and related settings. By default, this information is stored locally on your device.
We do not collect this workout data on Lauterstar servers, sell it, use it for advertising, or use it to track you across apps or websites.
Optional iCloud Sync
If you choose to sign in with Apple, Stack can sync your workout data through Apple's CloudKit using your private iCloud account. Apple handles that sync infrastructure under Apple's terms and privacy policies. Stack stores the Apple user identifier needed to keep you signed in and manage sync state.
You can use Stack without signing in. If you delete your Stack account, the app attempts to remove your synced CloudKit data. You may also choose whether to erase workouts stored on the current device.
Optional Apple Health
If you enable Apple Health integration, Stack requests permission to write completed workout records to Apple Health. Stack does not read your Apple Health data. You can manage Health permissions in the iOS Settings app.
Backups and Imports
Stack includes JSON export and import tools so you can back up or move your data. Exported files are controlled by you and may be saved to locations such as Files, iCloud Drive, or another storage provider you choose.
Optional Diagnostics and Product Insights
So we can fix bugs faster and understand which features actually help people train, Stack includes optional crash reporting and lightweight usage analytics powered by Firebase. Both are on by default and can be turned off any time in Settings → Privacy & Data.
Crash reports help us catch and fix the kind of failures we cannot reproduce on our own devices: stack traces, exception data, launch metrics. They are not linked to a user identifier.
Usage analytics record a small set of product interaction events: app open, workout start, workout complete (with the number of sets completed), custom exercise creation, export, import, settings open, theme change. The number of sets is the only event payload, and it is an integer count, not your weights or reps.
What we never send: your workout content, weights, reps, exercise names, routine names, notes, measurements, or anything that could identify you across other apps or websites. Stack does not call any "set user identifier" API, and the iOS privacy manifest declares NSPrivacyTracking as false.
Apple may also provide crash reports or diagnostics if your device settings allow that, separate from the Firebase reporting above. Our static website host may process basic technical logs, such as IP address, browser, and request information, to operate and secure the website.
Children
Stack is rated 9+ on the App Store. Stack is not directed to children under 9, and we do not knowingly collect personal information from children under 13. If a child under 13 uses Stack, a parent or guardian should supervise their use of the app and any optional Apple services.
Your Choices
You can keep Stack local-only, disable iCloud sync by signing out, revoke Apple Health permissions in iOS Settings, turn off crash reports or usage analytics in Settings → Privacy & Data, export your data, delete individual workouts or routines in the app, and delete your synced account data from the app's account section.