Period Trackers Ranked by Privacy: Which Apps Actually Protect Your Data
TLDR
Most period tracker apps store reproductive health data on company servers, which can be subpoenaed. Only apps using on-device storage — Floriva, Euki, and Drip — are structurally protected against legal compulsion. Flo has the worst documented record: an FTC enforcement action and $59.5M class action. Premom had an FTC enforcement action in 2023 for sharing data with Chinese analytics firms.
| App | Data Sold? | On-Device? | Account Required? | Price |
|---|---|---|---|---|
| Flo | Yes — FTC 2021, $59.5M class action 2025 | No | Yes | Free / $4.99/mo |
| Premom | Yes — FTC 2023 (shared with Umeng, Jiguang) | No | Yes | Free |
| Glow | Unknown — ad-supported model | No | Yes | Free / $79.99/yr |
| Ovia | Unknown — acquired by Labcorp | No | Yes | Free |
| Stardust | No documented history | No | Yes | Free / $7.99/mo |
| Spot On | No documented history | No | Yes | Free |
| Natural Cycles | No documented history | No | Yes | $12.99/mo |
| Clue | No documented history | No | Yes | Free / $9.99/mo |
| Euki | No — nonprofit, on-device | Yes | No | Free |
| Drip | No — open source, on-device | Yes — Android | No | Free |
| Floriva | No — on-device architecture | Yes | No | $2.99/mo |
How this ranking works
Privacy in period trackers comes down to two variables: data architecture and enforcement history.
Architecture is the structural question: does data live on your device only, or on company servers? On-device data cannot be subpoenaed because there is no server to serve. Server-based data can be compelled by a court, regardless of the company’s privacy policy.
Enforcement history is the track record: has the company been found to have violated its own privacy promises? FTC enforcement actions are public record.
The ranking below goes from worst to best.
Ranked worst to best: privacy
1. Flo (worst): FTC enforcement action 2021 for sharing health data with Facebook and Google. $59.5M class action settled September 2025 (Reuters 2025-09-25). Anonymous Mode is a paid feature that doesn’t change the server-based architecture. Jury found Meta liable for accessing Flo user data (Frasco v. Flo Health, August 2025).
2. Premom: FTC enforcement 2023 for sharing health data with Umeng and Jiguang (Chinese analytics firms) without consent. Server-based with account requirement.
3. Glow: Ad-supported model with server-based storage. No documented FTC enforcement, but the ad-supported architecture creates data use incentives. Acquired by a for-profit company.
4. Ovia: Acquired by Labcorp in 2021. Server-based with account requirement. New data handling context under a clinical diagnostics company introduces uncertainty about how health data may be used.
5. Stardust: Positions explicitly against data selling. No documented FTC enforcement. Server-based with account requirement — privacy is policy-based, not architectural.
6. Spot On (Planned Parenthood): Free, no ads, HIPAA-informed practices. No documented enforcement. Server-based with account requirement.
7. Natural Cycles: Sweden-based, GDPR-compliant, FDA-cleared for contraception. No enforcement history. Most expensive at $12.99/mo. Server-based.
8. Clue: Strongest privacy track record among major commercial apps. Berlin-based, GDPR-compliant, ad-free. No enforcement history. Server-based — but the best server-based option available.
9. Drip / Euki (tied, on-device): Both store data on-device with no account required. Drip is open source but Android-only. Euki is iOS + Android, broader features, nonprofit-backed. Neither has cross-device sync.
10. Floriva (best): On-device storage like Euki and Drip, with opt-in end-to-end encrypted cross-device sync. iOS and Android. No account required. $2.99/mo.
The bottom line on legal risk
Server-based apps can receive subpoenas. Apps with documented data-selling histories (Flo, Premom) have already demonstrated that your privacy promise is only as strong as the company’s next business decision. On-device apps (Floriva, Euki, Drip) are structurally protected: there is no data on a company server to compel.
If you’re switching to a private tracker, the architecture is what matters — not the marketing.
Neither feels private enough?
Floriva stores everything on your device. No data sold, no account required.
Verdict
On-device storage is the only structural protection against data subpoenas. Floriva, Euki, and Drip offer this. Among server-based apps, Clue and Natural Cycles have the cleanest enforcement records. Flo and Premom have documented FTC enforcement histories. Glow, Stardust, Ovia, and Spot On are server-based with no documented enforcement but still carry inherent subpoena risk.
PROS & CONS
Top Period Trackers (server-based)
Pros
- Free tiers available
- Cross-device sync
- Larger feature sets and prediction datasets
Cons
- Multiple documented FTC enforcement actions
- Server-based — all technically subpoenable
- Privacy depends on company policy, not architecture
PROS & CONS
Floriva (on-device)
Pros
- On-device storage — structural protection, not policy-based
- No account required
- Encrypted sync option that doesn't compromise architecture
Cons
- $2.99/mo
- Not FDA-cleared for contraception
- Newer product
Which period tracker is the most private?
The most private period trackers are those using on-device storage with no account requirement: Floriva, Euki, and Drip (Android). These apps store data exclusively on your device — there is no company server to subpoena. Among server-based apps, Clue and Natural Cycles have the cleanest enforcement records. Flo and Premom have documented FTC enforcement histories for sharing reproductive health data without consent.
Which period tracker apps have faced FTC enforcement?
Two period tracker apps have faced FTC enforcement actions: Flo Health in 2021 for sharing user health data (including period dates and pregnancy status) with Facebook, Google, and Flurry without consent; and Premom in 2023 for sharing sensitive health data with Chinese analytics firms Umeng and Jiguang without consent. Flo's conduct also resulted in a combined $59.5M class action settlement resolved in September 2025 (Reuters 2025-09-25).
Can period tracking data be used against you legally?
In states with abortion restrictions, period tracking data has been discussed as potential evidence in criminal proceedings. Data stored on company servers can be obtained via subpoena — the company must comply with valid court orders. Apps that store data only on your device cannot hand over what they don't hold. This is the practical legal difference between server-based apps (Flo, Clue, Glow) and on-device apps (Floriva, Euki, Drip).
Is Ovia safe after being acquired by Labcorp?
Ovia was acquired by Labcorp in 2021. Labcorp is a clinical laboratory and diagnostics company, which means the data could potentially be used in healthcare and research contexts beyond what Ovia's original privacy policy contemplated. Users should review Ovia's current privacy policy under Labcorp ownership. Ovia remains server-based with account requirements, so subpoena risk exists.
Frequently Asked Questions
What did Premom do with user data?
What is Spot On and is it private?
Does Clue sell period data?
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