Stardust app is sharing user health data with third parties

22:59 / 16.07.2026·34·Technology

Although the popular women's health tracking app Stardust promised its users data privacy, it has emerged that it is sharing sensitive medical information with analytics companies. Recent research by Mozilla investigators revealed that the app is sending users' personal data to the analytics platform RudderStack. This was reported by Techcrunch.com reports.

According to the Mozilla report, the transmitted data includes the user's date of birth, contraception type, reproductive goals, and even specific health symptoms. Although Stardust transmits this data without names, using a special identifier, experts do not consider this sufficient anonymity. The US Federal Trade Commission (FTC) has repeatedly warned that it is not difficult to link data to a specific individual using such identifiers.

Privacy promises vs. reality

Interestingly, Stardust promotes the slogan "Your data is private. Period." on its website. However, analyses conducted by TechCrunch and Mozilla researcher Shoshana Wodinsky showed that these claims are far from the truth. Previously, the company claimed that data was "end-to-end encrypted," but network traffic analysis revealed that the company itself has access to this information.

A Mozilla expert tested a total of six apps in this category. The results showed that Stardust was the only app sharing sensitive user health data with a third-party company. While other apps use external services for storage or payments, transmitting specific health details is considered a dangerous practice.

In a comment to BBC News, Stardust representatives emphasized that their contract with RudderStack prohibits the sale or use of data for their own purposes. However, since both companies operate under US jurisdiction, they may be compelled to provide user data if law enforcement agencies submit a request.

Safe alternatives for users

As a result of the study, experts also recommended safer options for users who prioritize personal data security. Specifically, the Mozilla study provided the following conclusions:

The Euki app was found to be the safest because it does not transmit data to third parties;
All health data is stored exclusively on the user's device;
When using apps like Stardust, it is recommended to carefully review privacy settings.

Today, digital security and personal data protection are becoming a global issue. Users should analyze which companies they entrust with their sensitive data when using foreign apps and, whenever possible, choose programs that store data only on the device itself (offline).