comparisons
Published by Floriva · Updated 2026-04-01 · How Floriva checks its guides
Flo, Clue, Natural Cycles Ranked by Privacy (2026)
We ranked 10 period trackers by data architecture. Flo's $59.5M settlement, Premom's FTC action, and the 3 apps that keep data on your phone.
Most period tracker apps store reproductive health data on company servers, which can be subpoenaed. Apps using on-device or local-first storage, Floriva, Euki, and Drip, reduce readable company-held data exposed to 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.
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 is less exposed to company-side legal requests because there is no readable server record. 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. Paid app with no free tier.
The bottom line on legal risk
Server-based apps can receive subpoenas. Apps with documented data-sharing histories (Flo, Premom) have already demonstrated that your privacy promise is only as strong as the company's next business decision. On-device and local-first apps (Floriva, Euki, Drip) reduce readable company-held data that can be compelled.
If you're switching to a private tracker, the architecture is what matters, not the marketing.
Cited signals
- Flo Health paid a $59.5M combined settlement for sharing reproductive health data without user consent Reuters / FTC, September 2025
All 10 Period Trackers Ranked by Privacy
| App | Data Sold | On-Device | Account Required | Price |
|---|---|---|---|---|
| Floriva | No, on-device architecture | Yes | No | Paid app (no free tier) |
| Euki | No, nonprofit, on-device | Yes | No | Free |
| Drip | No, open source, on-device | Yes, Android | No | Free |
| Clue | No documented history | No | Yes | Free / $9.99/mo |
| Natural Cycles | No documented history | No | Yes | $12.99/mo |
| Spot On | No documented history | No | Yes | Free |
| Stardust | No documented history | No | Yes | Free / $7.99/mo |
| Ovia | Unknown, acquired by Labcorp | No | Yes | Free |
| Glow | Unknown, ad-supported model | No | Yes | Free / $79.99/yr |
| Premom | Yes, FTC 2023 (shared with Umeng, Jiguang) | No | Yes | Free |
| Flo | Yes, FTC 2021, $59.5M class action 2025 | No | Yes | Free / $4.99/mo |
Strengths and trade-offs
Floriva (on-device)
Pros
- On-device storage, structural protection, not policy-based
- No account required
- Encrypted sync option that doesn't compromise architecture
Cons
- Paid subscription, no free tier
- Not FDA-cleared for contraception
- Newer product
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
What the experts say
These apps promised users privacy while systematically routing reproductive health data to third-party advertising networks. Policy claims were never backed by architecture.
Quick answers to the obvious questions.
Which period tracker is the most private
The most private period trackers use on-device storage with no account requirement: Floriva, Euki, and Drip (Android). These apps reduce readable company-held cycle data and company-side subpoena exposure. 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, and the company must comply with valid court orders. Apps that keep core records local-first create less readable company-held data to produce. Device access, backups, exports, and legal process remain separate risks.
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.
Which period trackers don't sell data
Apps with no commercial data incentive: Euki (nonprofit, Ibis Reproductive Health), Drip (open source, Android), and Floriva (paid, no ads). Flo, Glow, and Ovia have documented data-sharing histories or policies that permit it. Clue has no documented sales but still stores data on servers under GDPR rather than on-device.
Questions people ask before they switch.
What did Premom do with user data
The FTC took enforcement action against Premom's developer Easy Healthcare in 2023. The FTC alleged that Premom shared users' health data, including ovulation tracking information, with Chinese analytics firms Umeng and Jiguang without user consent. This was particularly notable given concerns about data handling by Chinese technology companies.
What is Spot On and is it private
Spot On is a period and birth control tracker from Planned Parenthood. It is free with no ads and has not faced FTC enforcement actions. However, Spot On stores data server-side and requires account creation, so it carries the same subpoena risk as other server-based trackers. Planned Parenthood's data handling practices are HIPAA-informed, but HIPAA covers healthcare providers rather than apps, and HIPAA compliance does not prevent law enforcement access.
Does Clue sell period data
Clue has not faced FTC enforcement for selling user health data. Clue is Berlin-based, GDPR-compliant, and operates without an ad-supported model. Clue does share data with research partners in specific, consented contexts. Clue's commercial privacy practices are notably better than Flo or Premom. The structural limitation is that data is server-based and technically accessible via legal process regardless of GDPR.