Flo vs Stardust: Period Trackers and What They Actually Do With Your Data

Flo vs Stardust vs Floriva: Data Handling Comparison
Feature	Flo	Stardust	Floriva
On-device storage	No	No	Yes
Account required	Yes	Yes	No
FTC enforcement history	Yes (2021)	No	No
Data can be subpoenaed	Yes	Yes	No
Privacy marketing emphasis	Low	High	Architecture-based
Astrology features	No	Yes	No
Price	Free / $4.99/mo	Free / $7.99/mo	$2.99/mo

Privacy as marketing vs privacy as architecture

Stardust launched with strong privacy-forward messaging. When Roe v. Wade was overturned, Stardust saw significant downloads from users looking for a safer alternative to Flo. That context matters: Stardust positioned against Flo’s data practices explicitly.

The positioning is better than Flo’s. No documented FTC enforcement. No class action settlements for data selling. But Stardust still requires an account and stores data server-side. The privacy claims are real in the commercial sense — Stardust appears not to monetize your data the way Flo did. The limitation is that commercial privacy commitments and legal compulsion are different things.

Flo’s track record

Flo is the most downloaded period tracker and has the worst documented data-sharing history in the category. The FTC found in 2021 that Flo shared users’ reproductive health data with Facebook, Google, and Flurry despite explicit privacy promises. A $59.5M class action settlement followed in September 2025 (Reuters 2025-09-25).

Flo’s Anonymous Mode, introduced post-settlement, is a paid feature. It reduces the data linkage within Flo’s systems but does not change the fact that data exists on Flo’s infrastructure.

What “policy-based privacy” actually means

Both Flo and Stardust’s privacy protection is policy-based: they make commitments about what they will and won’t do with your data. Policy controls can fail — either through corporate decisions, data breaches, or legal compulsion. A subpoena doesn’t ask permission.

Architecture-based privacy works differently. If data only exists on your device, there is no server to subpoena. Floriva, Euki, and Drip take this approach. The protection is not “we promise not to share your data” — it’s “we don’t have your data to share.”

Cost

Flo Free is functional. Flo Premium is $4.99/mo. Stardust Free and Premium at $7.99/mo. Floriva is $2.99/mo with on-device storage as the default for all users — no upsell required for privacy.

Neither feels private enough?

Floriva stores everything on your device. No data sold, no account required.

Verdict

Stardust markets itself more aggressively around privacy than Flo and has no comparable enforcement history. But both apps store data server-side — the privacy gap between them is in track record and policy, not architecture. For structural protection against subpoenas, neither app provides it.

PROS & CONS

Flo

Pros

Most feature-rich free tier in the category
Large dataset improves prediction accuracy
Comprehensive health logging

Cons

FTC-confirmed data sharing with Facebook and Google
$59.5M class action settled 2025
Privacy mode costs extra
Cloud-based storage with subpoena exposure

PROS & CONS

Stardust

Pros

Explicit anti-data-selling positioning
Unique astrology angle for interested users
No documented FTC enforcement history

Cons

Privacy is still policy-based — account and server required
Data technically accessible via legal process
Smaller user base means less data for predictions

PROS & CONS

Floriva

Pros

On-device storage — nothing on servers
No account required
Privacy enforced by architecture, not messaging

Cons

$2.99/mo
No astrology features
Smaller feature set at launch

Is Stardust a private period tracker?

Stardust markets itself with stronger privacy messaging than Flo and has not faced FTC enforcement actions. However, Stardust requires an account and stores data server-side. Privacy policies and promises are policy controls — they limit commercial data use but do not prevent law enforcement access via court order. Stardust's privacy posture is better than Flo's on record, but the architecture is similar.

What did Flo do with user data?

The FTC found that Flo shared users' reproductive health data — including period dates, pregnancy status, and health symptoms — with Facebook, Google, and Flurry despite promising confidentiality. The FTC took enforcement action against Flo in 2021. A combined class action settlement of $59.5M was reached in September 2025 (Reuters 2025-09-25). Flo launched Anonymous Mode after the enforcement action, but this feature requires a paid subscription.

Which period tracker has the best privacy?

Period trackers with on-device-only storage offer the strongest architectural privacy: Floriva, Euki, and Drip (Android). These apps store data exclusively on your device — no company server, no account required, nothing to subpoena. Among server-based trackers, Clue and Stardust have cleaner records than Flo. Among all trackers, on-device architecture is the only structural protection.

Frequently Asked Questions

Does Stardust period tracker sell data?

Stardust has positioned itself explicitly against data selling and has not faced the same enforcement history as Flo. Users should review Stardust's current privacy policy for specifics on data use. The key technical fact remains: Stardust stores data server-side, which means it is technically accessible to law enforcement regardless of the company's commercial data practices.

Is Flo still safe to use?

Flo is still operational and the most-downloaded period tracker. After the FTC enforcement action, Flo introduced Anonymous Mode. However, this mode requires a premium subscription ($4.99/mo) and the underlying architecture remains server-based. Whether Flo is 'safe' depends on what risk you're managing: if you're concerned about commercial data sharing, Anonymous Mode addresses some of that. If you're concerned about legal subpoenas in states with abortion restrictions, on-device storage is the only structural answer.

What is the difference between Flo Anonymous Mode and Floriva?

Flo Anonymous Mode severs the link between your health data and your email address within Flo's system — but Flo has confirmed the data still exists on their infrastructure. Floriva stores data only on your device. Floriva's data protection is architectural: there is no server, there is no account, there is nothing to anonymize or sever because it never left your device.

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