Sync vs Flow
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Sync
A privacy-focused period tracker that stores all your data locally on your device. It offers a simple and ad-free experience for managing your menstrual cycle.
- Privacy-focused design
- Local data storage
- Ad-free experience
- Simple interface
- Cycle tracking
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Sync Period tracks cycles locally and supports private sharing with a partner or friend. Log periods, symptoms, moods, and notes; view your calendar and pattern summaries; set optional reminders; and import supported Flo, Clue, Drip, or generic CSV data after reviewing what Sync can recognize. Your cycle history is encrypted on your device. Private predictions adapt to your recent cycle history and confirmed corrections entirely on your device. Sync shows a likely-start window and confidence level, learns recurring pre-period patterns, and can use an enabled BBT signal or positive ovulation test without uploading those health details. Predictions become more cautious when history is sparse or variable. Partner sharing is optional and off by default. You choose which supported cycle details to share. Updates are end-to-end encrypted and require the complete private invite to open. Each encrypted relay update expires after no more than 30 days; active sharing renews that rolling expiration when a new update is published. Recent physical symptoms and flow, sex-drive and intimacy check-ins, and moods are three separate opt-ins that can each be turned off again. Intimate sharing is off by default and never indicates consent. Discharge, medications, written notes, and other sexual details remain private. Sync Period has no ads, no behavioral analytics SDKs, and no required account. You can export a private backup or permanently delete local app data at any time. Cycle predictions and pattern summaries are estimates. Sync Period does not provide diagnosis, contraception, or medical advice.
Flow
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FlowSync is your intelligent period and cycle tracking companion. With a beautiful, intuitive calendar interface, FlowSync helps you understand your body's natural rhythms. KEY FEATURES: • Smart Calendar — Visual cycle tracking with color-coded days for period, fertile window, and ovulation • Period Predictions — AI-powered cycle predictions based on your history • Symptom Tracking — Log mood, energy, cramps, and other symptoms daily • Today View — At-a-glance dashboard showing cycle day, phase, and upcoming events • Cycle Insights — Understand your patterns with detailed cycle analysis • Beautiful Design — Clean, modern interface that's a joy to use FlowSync is designed for informational and general wellness purposes only. It is not intended to be used for contraception, medical advice, diagnosis, or treatment. Always consult your healthcare provider for medical concerns.
Screenshots
Verdict
The clearest difference is device support: Sync at 3 against Flow's 1. Sync also leads on iOS requirement (15.1 vs 17.0). On price, update cadence, ads and in-app purchases there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
Both ship on a similar rhythm, roughly every 3 weeks. The most recent releases landed on October 3, 2026 and October 6, 2026 respectively.
| Parameter | Sync | Flow |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (1 ratings) — better | — |
| Positive reviews | 100.0% of reviews | — |
| Number of ratings | 1 — better | — |
| Update frequency | Every 3 weeks | Every 3 weeks |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | — |
| Devices | iPhone, iPad, iPod — better | iPhone |
| Requires iOS | 15.1 — better | 17.0 |
| Further details — not scored | ||
| Size | 41 MB | 4 MB |
| Age rating | 12+ | 4+ |
| Developer | Wei Jian Wong | 拥军 刘 |
In-app purchases
Sync
No in-app purchases
Flow
No in-app purchases








