Story perspectives

Mozilla Rates Period Apps: Euki Perfect, Stardust Shares Data

7/19/2026

Summary

Story summary

Mozilla’s Privacy Not Included team published a study rating six period-tracking apps on reproductive-health data.
Euki earned a perfect 10-out-of-10 for local storage, no account and permissions, while Clue scored 8, Flo 7, Period Calendar 6, Spot On 5 and Stardust 2.
Stardust sent birth dates, birth-control methods, reproductive goals and symptoms to RudderStack and advertisers like AppsFlyer and Facebook while Flo and Period Calendar also shared device IDs with analytics platforms.

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Story summary

Mozilla’s Privacy Not Included team published a study rating six period-tracking apps on reproductive-health data.
Euki earned a perfect 10-out-of-10 for local storage, no account and permissions, while Clue scored 8, Flo 7, Period Calendar 6, Spot On 5 and Stardust 2.
Stardust sent birth dates, birth-control methods, reproductive goals and symptoms to RudderStack and advertisers like AppsFlyer and Facebook while Flo and Period Calendar also shared device IDs with analytics platforms.