Cycle tracking has unique stakes. We weight privacy and data ethics as heavily as accuracy for this category — and that means our ranking diverges sharply from the typical “most downloads” lists.
Why cycle tracking is high-stakes data
Reproductive-health data is among the most sensitive personal data anyone holds. The EFF and Mozilla’s *Privacy Not Included project have spent years documenting how period apps share data with advertisers, brokers, and in some cases law enforcement. The Office on Women’s Health and ACOG both recognize cycle tracking as clinically valuable — but the how of where your data lives matters.
Our ranking weights:
- Privacy posture (40%): local-only vs. cloud, account requirement, third-party sharing, encryption.
- Prediction accuracy (30%): period and fertility-window prediction error over 3+ months of use.
- Symptom tracking depth (15%): customizability of inputs, integration with body-temperature data.
- Editorial independence (15%): is the app funded by ads, by users, or by a mission-driven org?
How we tested
- Three reviewers used each app for ≥3 cycles
- Privacy reviews cross-checked against Mozilla and EFF reports
- Prediction accuracy measured against actual period onset dates
Benchmark scoreboard
At-a-glance comparison of every Menstrual Cycle app in this ranking. Sorted by overall score; higher is better.
| # | App | Score | Tier | Pricing | Standout strength |
|---|---|---|---|---|---|
| #1 | 9.3 | Excellent | Freemium · Free | Strongest privacy posture in the category | |
| #2 | 9.1 | Excellent | Freemium · Free | Open source | |
| #3 | 8.2 | Strong | Premium · $89.99/yr | FDA-cleared | |
| #4 | 7.8 | Solid | Freemium · Free · Plus $39.99/yr | Excellent UX | |
| #5 | 6.4 | Mixed | Paid · Premium $39.99/yr | Feature breadth |
The rankings, in detail
Euki 9.3 / 10
Built for privacy. No account, no cloud sync, all data local on your device. Funded by a reproductive health nonprofit.
Pros
- Strongest privacy posture in the category
- No tracking, no ads
- Free
Cons
- No cross-device sync (by design)
Drip 9.1 / 10
Open source, offline-first cycle tracker built with symptothermal users in mind.
Pros
- Open source
- Strong FAM/NFP features
- Local-only data
Cons
- UI is functional rather than polished
Natural Cycles 8.2 / 10
FDA-cleared contraceptive app — proven efficacy, but data lives in the cloud.
Pros
- FDA-cleared
- Solid algorithm
Cons
- Cloud data storage
- Subscription
Clue 7.8 / 10
Well-designed, science-forward, but data policies merit reading.
Pros
- Excellent UX
- Research-backed content
Cons
- Cloud-based
Flo 6.4 / 10
Massive user base but historical data-sharing concerns drop it down our list.
Pros
- Feature breadth
Cons
- Past data-sharing settlements with the FTC weigh against it