Period Tracker Apps Under Fire for Privacy Violations
Original: Your Period Tracker Is (Probably) Spying on You
Why This Matters
Reproductive health data privacy is a critical legal and safety concern, especially post-Roe v. Wade.
A Mozilla Foundation audit of six popular period tracking apps, conducted with Harvard's Berkman Klein Center, found that Stardust sends users' reproductive health data to a third-party analytics firm not listed in its privacy policy, scoring 2 out of 10. Nonprofit app Euki received a perfect score.
A Mozilla Foundation audit partnered with Harvard's Berkman Klein Center evaluated six popular period tracking apps for privacy practices. The astrology-themed app Stardust scored 2 out of 10 — the worst in the group. Mozilla researcher Shoshana Wodinsky found that Stardust pings third-party trackers the moment it opens, even before users enter any data. When a symptom is logged, the details — including birth control type, pregnancy status, moods, and specific symptoms — are sent to analytics firm RudderStack alongside a persistent user ID, with no in-app option to disable sharing. RudderStack is designed to route data onward to further destinations that Mozilla could not observe. Stardust also passes Facebook an ad identifier linking in-app behavior to existing platform profiles. The company stated it has never received a legal demand for user data. In contrast, nonprofit-run tracker Euki earned a perfect 10. It requires no account, stores all health data locally on the device, and offers features such as PIN protection, automatic deletion scheduling, and a decoy screen. The audit highlights significant privacy risks associated with reproductive health data collected by commercial apps.