Best period tracker app for privacy in 2026: 6 questions that decide it

Which cycle app is safest for your data? Six questions to test any app in two minutes, plus how Flo, Clue, Natural Cycles and PERIOD. compare.

Written by the PERIOD. team. We make a cycle app ourselves; the questions below apply to us just as much. As of October 2026.

Short answer: the "best" period tracker for privacy is one that is based in the EU, never sells your health data or uses it for advertising, publishes a list of its sub-processors and lets you delete everything in one tap. You can check all of that yourself in two minutes.

The 6 questions

1. Where is the company based and where is your data stored? In the EU the GDPR applies and cycle data gets extra protection.
2. Does the policy literally say they do not sell your health data? Vague phrases like "shared with partners" are a red flag.
3. Is there a public list of sub-processors? No list means you do not know who else can see your data.
4. Does anything go to ad networks? Read which events are shared, and whether any health data is included.
5. Can you export and delete your data? Test it: can you find out how within two minutes?
6. Is there a track record? Search the app's name with "FTC", "fine" or "lawsuit".

How do the well-known apps compare?

• Clue: Berlin, GDPR, says it never sells health data (helloclue.com).
• Natural Cycles: Swedish medical company, works under medical device rules (naturalcycles.com).
• Flo: settled with the US FTC in 2021 over sharing health data with analytics services, followed by a class action settlement in 2026; Flo denied wrongdoing and now offers an anonymous mode (FTC, HIPAA Journal).
• PERIOD.: Dutch, data stored encrypted in Frankfurt, sells nothing, health data never goes to advertisers. We measure our own ads with a few events without health data (such as "trial started"), and that is stated in our privacy policy. Every sub-processor is on one page.

Why this matters

Cycle data says something about your health, your sex life and a possible pregnancy. Picking an app takes two minutes; getting your data back is not possible.

General information, not legal advice. Brand names belong to their owners; always check the current details with the app itself.

Download PERIOD. on the App Store or on Google Play. The basics stay free.