Flo vs Stardust 2026: Privacy, Features & Price Compared

Flo and Stardust occupy opposite ends of the period tracker spectrum in brand positioning. Flo is the established market leader — 440 million users, comprehensive features, and a corporate health platform approach. Stardust is the post-Dobbs privacy challenger — a smaller app that surged in downloads after the Supreme Court's decision by marketing itself as a privacy-first period tracker with astrology-themed insights.

Flo offers depth: AI chatbot, 70+ symptoms, community forums, pregnancy mode, and content from 120+ medical experts. Stardust offers differentiation: astrology-blended cycle insights and privacy messaging that resonated with users suddenly concerned about their menstrual data.

The irony is that neither app delivers on privacy. Flo was proven to share data with advertisers. Stardust's privacy claims didn't survive independent investigation. For users who care about reproductive data privacy — especially in a post-Dobbs landscape — neither app provides architectural protection.

The privacy comparison between Flo and Stardust is a case study in two different kinds of failure: proven betrayal versus misleading promises.

Flo's violations are documented in court. Sharing menstrual data with Google, Meta, and analytics firms. A $56M class action settlement. A California jury finding Meta guilty of eavesdropping. Flo did the thing everyone fears a period tracker will do.

Stardust positioned itself as the antidote to Flo's failures. After the Dobbs decision, it marketed privacy and surged in downloads. But in June 2022, Vice/Motherboard discovered Stardust's privacy policy stated it would cooperate with law enforcement "whether or not legally required" — meaning voluntary handover of menstrual data to police. Stardust changed the wording only after press inquiry.

Then in May 2025, Privacy International revealed deeper issues: Stardust sends data to servers and relies on Rownd, a third-party de-identification service. A Google account is required, linking your menstrual data to Google's identity ecosystem. De-identification is a process, not a guarantee — academic research shows menstrual data can be re-identified with few data points.

PinkyBloom provides what both apps promise but fail to deliver: actual privacy. On-device storage, no accounts, no servers, no third-party de-identification services. Safety Mode hides the app's data instantly. The privacy is architectural, not aspirational.

Flo's feature set dwarfs Stardust's. AI chatbot, 70+ symptoms, community forums, pregnancy mode, and thousands of articles. Flo is a comprehensive health platform.

Stardust's main differentiator is astrology-themed cycle insights — connecting your cycle to astrological concepts. The tracking itself is basic: cycle predictions and symptom logging. For users who enjoy the astrology angle, it's engaging. For users who want health intelligence, it's limited.

PinkyBloom provides genuine AI intelligence. On-device AI handles health conversations, voice logging captures symptoms naturally, mood forecasts predict emotional patterns, and doctor visit reports create professional summaries. It's the substance that both Flo's chatbot and Stardust's astrology insights point toward, but delivered privately on your device.

Flo charges ~$49.99/year for premium; its free tier has ads. Stardust is free with no ads.

Both apps store data in the cloud. Flo monetizes through subscriptions and (historically) advertising partnerships. Stardust's monetization model is less clear, but the Google account requirement and server-side data processing suggest data plays a role.

PinkyBloom is free with every feature included. No subscription, no ads, no Google account linkage. The total cost is $0 with the strongest privacy architecture in the category.