How to keep your cycle data on your iPhone

You can track your cycle without your log sitting on a company's server. These steps work with any app, Isla included.

1. Choose an app that does not need an account

If an app makes you sign up before you can log a period, your log is stored with that account. Look for an app you can use with no sign-in at all, and check that it does not ask for one later to unlock export or backup.

2. Check the privacy label against the description

On the App Store page, the App Privacy section should match what the description promises. A listing that says your data never leaves the phone, next to a label that lists Health or Sensitive Info as linked to you, is worth a second look.

3. Watch what it connects to

Turn on App Privacy Report (Settings, Privacy and Security, App Privacy Report). After a week of normal use, open the app's entry and look at the domains it contacted. Advertising and analytics domains from other companies tell you outside code is running.

4. Decide about Apple Health

Apple Health's Cycle Tracking keeps its data on the iPhone. If you sync Health with iCloud, Apple's iCloud security overview lists Health data among the categories that are end-to-end encrypted. Many period apps can read from or write to Health; each needs your permission per data type, which you can review in the Health app under Sharing, Apps.

5. Know what your backups hold

An iCloud Backup of your iPhone includes app data, which is how your log moves to a new phone. With standard protection Apple holds the keys to iCloud Backup; turning on Advanced Data Protection (Settings, your name, iCloud) makes iCloud Backup end-to-end encrypted. A backup to a Mac or PC with "Encrypt local backup" switched on stays on that computer.

6. Keep your own export

An app that lets you export your whole log as a file, without asking support or creating an account, means you are never locked in. Save the file somewhere only you control. See how to export and delete period data.

In Isla

Isla is used without an account. Your log is kept in Isla's storage on the iPhone, and Apple Health sync is off until you turn it on. Settings, Your log, Export a copy saves your whole log as JSON or CSV; Delete everything erases it from the phone.