Period tracker Stardust shares users' health data with analytics firm

Mozilla research found that period tracker Stardust transmitted users' health data to analytics firm RudderStack. The data included birthdate, birth control type, reproductive goals, and reported symptoms, each linked to a unique identifier. The FTC has previously warned that such identifiers do not prevent re-identification of individuals.

The sharing occurred in the background and was not visible to users.

Privacy practices compared Of the six apps examined, Stardust was the only one observed sending sensitive health data to another company. Mozilla recommended Euki as the only app that kept all core health data on the user's device. A Stardust spokesperson told BBC News that RudderStack is contractually barred from selling the data or using it for its own purposes.

Both companies remain subject to U.S. law enforcement requests for stored records. TechCrunch previously reported in 2022 that Stardust's claim of end-to-end encryption was contradicted by network traffic analysis. The same method was used in the Mozilla study.