Privacy Guides

The FTC took enforcement action against Flo in 2021 for sharing reproductive health data with Facebook and Google. A $59.5M class action settled in 2025. Here's what actually happened.

End-to-end encryption and zero-knowledge architecture are not the same thing. This guide explains the difference and what each actually protects you from.

Free period tracker apps have a business model. This guide explains how femtech companies monetize health data, what the FTC enforcement record shows, and how to audit what your app is sending.

Period tracker apps collect far more than cycle dates. This guide explains what data is collected, how it is used, and what the FTC enforcement actions against Flo and Premom revealed.

Most users skip privacy policies. This guide gives you a 5-step checklist to audit any period tracker's privacy policy in under 15 minutes — and shows you exactly what to look for.

You do not need an app to track your menstrual cycle. This guide covers paper tracking, spreadsheet methods, and on-device apps that store nothing on a server.

Irregular cycles are harder to track but more important to document. This guide explains what counts as irregular, how to build a useful baseline, and when to discuss findings with a healthcare provider.

On-device storage means your health data never leaves your phone. This guide explains what that means, why it matters legally, and how it differs from cloud-backed storage.

Open source period trackers allow anyone to inspect the code and verify privacy claims independently. This guide explains what open source means, its limits, and how to evaluate an open-source app.

In states with abortion bans, law enforcement can subpoena period tracker data from cloud-based apps. On-device apps cannot be compelled to hand over data they don't have. Here's exactly how it works.

Most period tracker apps are not covered by HIPAA. This guide explains which law actually governs consumer health apps, what protections you do and do not have, and what the FTC can do.

Period tracker apps use calendar math, BBT, and sometimes LH data to predict ovulation. This guide explains each method, its accuracy, and where predictions commonly fail.