Comparing period apps in 2026: what actually matters

There are hundreds of cycle apps, and from the outside they look alike: a calendar, a prediction, some symptom icons. The difference sits under the hood — in what happens to your data and what is locked behind a paywall. These are the questions we would ask, plus our own answers.

1. Where is your data stored, and which law applies?

If the app is based in the EU, the GDPR applies and cycle data counts as special category data with extra protection. If it is based elsewhere, the question is which safeguards cover the transfer. Look in the privacy policy for the company's location and for "international transfers".

PERIOD.: Dutch company, data inside the EU, GDPR applies. See our privacy policy and our sub-processor list.

2. Which third parties get to see something?

Any serious app publishes a sub-processor list: hosting, crash reporting, analytics, payments. No list means you know nothing. An ad network on the list tells you plenty.

3. Is your data sold or used for advertising?

Watch for phrasing like "shared with partners for marketing purposes". That is where things go wrong. An app that is clear about it writes one sentence: we do not sell your data.

PERIOD.: we do not sell data and we do not use your cycle data for advertising.

4. What is free, and what costs money?

Freemium is not wrong, but check where the line sits. If basic things — reviewing your own history, understanding your phase — are behind a subscription, you are paying for insight into your own body.

PERIOD.: the basics stay free. PERIOD. plus is optional (€3.99 per month) for extra features. More in why the basics stay free.

5. Can you export and delete your data?

You have the right to a copy of your data and to deletion. Practical test: can you find out how within two minutes? If not, that is an answer too.

PERIOD.: export and deletion are available — see delete my data.

6. How careful is the app around pregnancy and fertility?

An app that keeps nudging you toward conception when that is not where you are is not neutral. Pick something where you choose your own goal — and where no app pretends to be contraception. Cycle tracking is not, ours included.

7. Does the app work in your own language?

Describing symptoms in your first language is the difference between logging consistently and quitting after two weeks. Check whether help texts and support are localised too.

8. How honest are the predictions?

No app can pinpoint ovulation from calendar data alone. A good app says so, and gives you a range instead of false certainty. See calculating ovulation.

How to use this list

• Open the privacy policy and search for "sell", "advertising", "partners" and "transfer".
• Find the sub-processor list. No list, no transparency.
• Test inside the app: export, delete, change your goal.
• Find the paywall before you log for months.

FAQ

Is a European app automatically safer? Not automatically, but the GDPR gives you stronger rights and imposes stricter duties on the provider.

Can I take my history to another app? Usually yes, via a data export. See our guide to switching apps.

This article is general information, not legal or medical advice.

Want an app that answers these questions without hedging? Download PERIOD. on the App Store or on Google Play. The basics stay free.