Ondi vs Cycle Sync
Price, ratings, monetisation and update history for both apps, side by side β with what reviewers say about each.
Ondi
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Private period tracking, with daily logs and cycle history on your device. No account required. Ondi learns your unique cycle and gives you personalised insights that get smarter with every log. WHAT'S FREE β ALWAYS β’ Period tracking with automatic cycle detection β’ Daily logging: flow, mood, energy, sleep, symptoms β’ Cycle predictions that improve over time β’ Calendar with cycle history β’ Cycle irregularity alerts UNLOCK EVERYTHING (one-time purchase) β’ Fertility tracking: temperature, cervical mucus, ovulation tests β’ Contraception side effect matching β’ Headache and migraine pattern detection β’ PMS prediction and sleep analysis β’ Exercise guidance tailored to your cycle phase β’ Trying to Conceive mode with timing insights β’ Pregnancy mode: week-by-week guidance and due date β’ Postpartum recovery tracking β’ Data export for doctor appointments PRIVACY FIRST Your logs are stored on your device. Ondi does not operate a server for your health records or use tracking analytics. Apple Health access is optional, and you choose when to export or share a report. Copies you export and data stored in Apple Health are managed separately. EVERY STAGE OF YOUR JOURNEY From first periods to menopause, Ondi adapts. Perimenopause pattern detection, postpartum period return guidance, and breastfeeding-aware insights β all explained in plain language. WORKS WITH APPLE WATCH Reads wrist temperature and heart rate data from Apple Health to enhance predictions without manual tracking. Ondi is not a medical device and should not be used as contraception. Predictions are estimates. Always consult a healthcare provider for medical decisions.
Cycle Sync
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CYCLE-AWARE CALENDAR CycleSync helps professional women align their work schedules with their natural menstrual cycle phases. Instead of fighting through low-energy days, you get smart suggestions to move demanding meetings to days when your focus and energy peak. WORK WITH YOUR RHYTHM, NOT AGAINST IT Your cycle isn't an obstacle. It's a compass. Menstrual Phase (Winter) Rest and recovery. Reschedule high-stakes meetings. Follicular Phase (Spring) Rising energy. Schedule creative work and planning. Ovulation Phase (Summer) Peak performance. Take on negotiations and leadership. Luteal Phase (Autumn) Focused wind-down. Finish projects and organize. SMART RESCHEDULING CycleSync connects to your calendar and automatically detects: β’ Events on heavy-flow days β’ Events on rest-phase days β’ Dense meeting days during focus phases (3+ events) One tap on a conflict card opens the Time Slot Picker. Your available slots on better days are pre-calculated. Reschedule in seconds. An undo option gives you 10 seconds to reverse. RULES, NOT GUESSWORK. The recommendation engine is rule-based: 1. Your cycle history predicts your phase for any date. 2. Your phase preferences determine focus or rest classifications. 3. Your calendar events are flagged when they conflict with your classifications. 4. Available slots on recommended-phase days enable one-tap rescheduling. EVERYTHING IN ONE SUBSCRIPTION An active CycleSync Pro subscription unlocks the whole planner: β’ Cycle logging, phase prediction and a 14-day cycle outlook β’ Dashboard with today's phase and a 7-day week view β’ Calendar sync with Apple Calendar and Google Calendar β’ Conflict detection and unlimited reschedule suggestions β’ One-tap rescheduling with a 10-second undo β’ Five notification types: reschedule alerts, phase transitions, period predictions, tomorrow's preview and re-engagement nudges β’ Insights: energy curve, seasonal capacities and full cycle history β’ Cycle import from Apple Health β’ Export your cycle history as JSON or CSV β’ Light, Dark and System themes BEFORE YOU SUBSCRIBE Onboarding and the plan comparison are free, so you can see how CycleSync works before you pay. The planner opens once your subscription is active, and everything you have already logged stays on your device. Weekly, monthly and yearly plans are available in the app. PRIVACY FIRST β’ All cycle data is stored locally on your device β’ No cloud sync and no tracking β’ Health data is read-only from Apple Health β’ Export your data anytime as JSON or CSV HOW TO START 1. Open CycleSync and log your last period start date. 2. Connect your calendar using Apple Calendar or Google Calendar. 3. Set your typical cycle length (default: 28 days). 4. Review your dashboard. Suggested reschedules appear automatically. Download CycleSync and work with your natural rhythm. By subscribing, you agree to our Terms of Use (EULA): https://cyclesync.tunnxo.com/legal/eula.html Privacy Policy: https://cyclesync.tunnxo.com/legal/privacy.html
Screenshots
Verdict
The clearest difference is ads: Ondi at none against Cycle Sync's shown. Ondi also leads on update cadence (weekly vs every 2 months). On price, in-app purchases, device support and iOS requirement there is nothing between them.
Scored on Price Β· Rating Β· Positive reviews Β· Number of ratings Β· Update frequency Β· Ads Β· In-app purchases Β· Monetization Β· Best chart rank Β· Devices Β· Requires iOS
Both are free to download. Ondi sells 1 one-off in-app purchase and Cycle Sync sells 3 in-app purchases, starting at $4.99 per 7 days. Whichever you choose, the download price is not the number that matters.
Ondi ships an update weekly, Cycle Sync every 2 months. The most recent releases landed on October 28, 2026 and October 24, 2026 respectively.
| Parameter | Ondi | Cycle Sync |
|---|---|---|
| Price | Free | Free |
| Update frequency | Weekly β better | Every 2 months |
| Ads | No β better | Yes |
| In-app purchases | Yes | Yes |
| Devices | iPhone, iPad | iPhone, iPad |
| Requires iOS | 17.0 β better | 18.2 |
| Further details β not scored | ||
| Size | 10 MB | 78 MB |
| Age rating | 12+ | 4+ |
| Developer | Blue Flame Games | Amit Kairon |
In-app purchases
Ondi
- Cyla Premium$7.99
Cycle Sync
- CycleSync Pro β Weekly$4.997 Days
- CycleSync Pro$9.991 Month
- CycleSync Pro$59.991 Year









