islaWhat a period tracker app can see about you
A period tracker holds some of the most personal data on a phone. What it can see, and where that data goes, depends on four things you can check before you log anything.
1. What you type into it
Start dates, flow, spotting, symptoms, moods, sex, test results, temperatures and free-text notes. In the US, Washington's My Health My Data Act treats this as consumer health data, and in the EU it is special-category data under Article 9 of the GDPR. Whether any of it leaves the phone is a design choice made by the app's developer.
2. What the phone adds
Any app that connects to the internet shows its server the phone's IP address, and usually the device model and iOS version. It can also read the advertising identifier, but only if you tap Allow when it asks to track you; Settings, Privacy and Security, Tracking lists every app that has asked. Location, contacts and photos each need their own permission.
3. The account
An app that asks you to sign up links your log to an email address, an Apple or Google sign-in, or a phone number. Your data then lives on the company's servers as well as your phone, under its privacy policy and the law of the places it operates. An app with no account has nothing to link your log to.
4. Code from other companies inside the app
Many apps include analytics, advertising, crash reporting or attribution kits written by other companies. Those kits receive whatever the app passes to them. In 2021 the US Federal Trade Commission settled with the maker of Flo over allegations that the app sent app events, including ones describing what users entered, to outside analytics providers while promising to keep health data private (FTC case 1923133). Flo did not admit wrongdoing.
How to check an app on an iPhone
- The privacy label. Scroll to App Privacy on the App Store page. It shows what the developer says is used to track you, linked to you, or collected but not linked to you. See how to read a privacy label.
- App Privacy Report. Turn it on in Settings, Privacy and Security, App Privacy Report. After a few days it lists the internet domains each app contacted. An app that keeps your log on the phone should contact very few.
- The privacy policy. Look for a list of service providers or processors, and whether it says health data is shared, sold or used for advertising.
What Isla sees
Isla has no account and no server for your log; everything you log is kept on your iPhone. It sends a handful of anonymous app events to analytics that Tundra Industries runs itself (the app opened, setup finished, a day was logged, the Pro screen appeared, a purchase went through), tied to a random install number and never to what you logged. It contains no code from advertising or analytics companies.