Mozilla Ranks Euki Top Period Tracker With 10/10 Privacy Score, Stardust Last at 2/10
Updated
Updated · CyberInsider · Jul 17
Mozilla Ranks Euki Top Period Tracker With 10/10 Privacy Score, Stardust Last at 2/10
3 articles · Updated · CyberInsider · Jul 17
Summary
Euki was the only app to earn a perfect 10/10 in Mozilla’s review of six period trackers, while Stardust ranked last at 2/10 after researchers observed broad third-party tracking and health-related data flows.
Hands-on testing and network analysis found some apps exposed device identifiers, usage details or sensitive logs to analytics and ad systems, even when actual cycle records were not directly shared with advertisers.
Euki scored highest because it stores health data locally, requires no account and limits permissions, though Mozilla found external sites opened in its in-app browser could still load Google, Meta and Microsoft trackers.
Clue scored 8 and Flo 7, with Mozilla saying both offered stronger controls but still built extensive long-term health profiles; Flo’s Anonymous Mode reduced tracking, though an Apple device identifier had already been sent before activation.
Mozilla said the findings matter more after the Dobbs ruling because simply using a reproductive-health app can become part of a persistent profile that may carry legal and privacy risks.
Period apps use your data for AI predictions. Can you get smart features without sacrificing your personal privacy?
If 'free' health apps are funded by your data, what is the true cost of monitoring your own body?
Can new state laws truly stop period trackers from selling your most sensitive health data to data brokers?
2026 Privacy Audit: Mozilla Exposes Data Sharing Risks in Top Period and Ovulation Apps
Overview
Mozilla Foundation’s July 2026 privacy review exposed how six popular period and ovulation tracking apps handle sensitive user data. The investigation found that, despite strong privacy claims, the Stardust app was sharing reproductive details with an analytics company, RudderStack. Stardust disputed this, saying no personal information was shared, but the disagreement highlights how difficult it is for users to truly know where their health data goes. This gap between what apps promise and what actually happens shows why users must be cautious and why greater transparency is urgently needed in the digital health space.