Synca vs Red Diary
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Synca
This app uses AI to help you plan your daily tasks and activities around your menstrual cycle. It provides personalized insights and suggestions for energy, focus, and mood based on your current cycle phase. Optimize your productivity and well-being by working with your body's natural rhythms.
- AI-powered cycle-aware task planning
- Personalized daily insights based on cycle phase
- Four cycle phases with identified strengths
- Smart calendar with energy-based event tagging
- Quick daily mood and energy tracking
- Phase-matched workout and meal suggestions
- Private data storage on device
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Synca helps you plan your days around your menstrual cycle, not against it. Powered by AI and backed by science. Your hormones affect your energy, focus, and mood every single day. Synca reads your cycle phase and tells you when to push hard, when to communicate, and when to rest. Stop guessing why some days feel harder than others. CYCLE-AWARE PLANNING Brain dump your tasks — Synca's AI sorts them into your day based on your current cycle phase and energy levels. The right task, at the right time, in the right phase. 4 PHASES, 4 SUPERPOWERS Menstrual, follicular, ovulatory, luteal — each phase brings different strengths. Synca color-codes your entire month so you always know what's coming and how to prepare. AI DAILY INSIGHTS Every morning, get a personalized insight based on where you are in your cycle. What to expect, what to prioritize, and how to make the most of your day. SMART CALENDAR Your events tagged with cycle-aware energy badges — "Peak performance", "Go gentle", "Deep focus." See your schedule through the lens of your biology. TRACK IN 10 SECONDS Log your mood, energy, and symptoms with a quick daily check-in. The more you track, the smarter Synca gets. MOVE & NOURISH Workout and meal suggestions matched to your phase. HIIT when you peak. Yoga when you rest. Iron-rich foods during menstrual. Complex carbs in luteal. Science-backed, not generic. PREDICTIONS THAT LEARN Period predictions, cycle trends, and personal patterns and all getting smarter with every cycle you complete. PRIVATE BY DESIGN All health data is stored locally on your device. No account required to get started. No data sold. No third-party trackers. Your body, your data. Built by a woman, for women. Synca exists because your productivity tools should understand your biology. Full access available with a 1 month free trial subscription. Terms of Use: https://hellosynca.co/terms
Red Diary
This app analyzes your symptoms, mood, energy, sleep, and activity to provide personalized insights and daily guidance tailored to your cycle phases. It offers a body weather forecast and smart recommendations for exercise, nutrition, and self-care.
- Personalized cycle insights
- Smart daily guidance
- Body weather forecast
- Cycle tracking modes (fertility, pregnancy, birth control)
- Symptom and mood logging
- HealthKit integration
- Apple Watch companion app
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A period and cycle tracker that keeps your data on your phone. No account. No cloud. No tracking. No ads. Most period apps send your most private information to their servers. Red Diary doesn't have servers. Free to track your cycle, log symptoms, and get predictions — no trial, no card, no expiry. Premium unlocks the fertility, pregnancy, and insight modes. PRIVATE BY DESIGN Your cycle history, symptoms, and intimate details never leave your device. There is no account to create, no server to breach, and no company reading your data. Export anytime for a doctor's visit or your own backup — it's your information. BUILT FOR REAL CYCLES, NOT AVERAGE ONES Most trackers assume a textbook 28 days and get confused when yours doesn't cooperate. Red Diary reads each cycle on its own terms, so irregular, long, short, and changing cycles are understood instead of flagged as wrong. BODY WEATHER Your own forecast, built from your own logs. Red Diary looks for patterns across your history and tells you what today has tended to look like for you — sunny, clear, mixed, overcast, or stormy. If it doesn't have enough history to say something true, it tells you that instead of guessing. WHAT SHOULD I DO TODAY? Every time you open the app, you get an answer. Phase-aware guidance for movement, food, and rest that shifts as your body does. FOUR MODES Track My Cycle — phase-by-phase analytics and predictions Trying to Conceive — fertile window, peak day, cycle health, and support through the two-week wait Avoid Pregnancy — honest fertility status, including the days it can't be certain about I'm Pregnant — 40 weeks of content, kick counter, appointments, and trimester insights Switch whenever life changes. The app changes with you. A CALENDAR THAT ACTUALLY WORKS Start and end your period with one tap, right from the calendar. Backdate cycles you missed. Log intercourse. See period, predicted, fertile, and logged days at a glance — with moon phases, if you like tracking alongside them. WHY YOU FEEL LIKE THIS Log symptoms, mood, sleep, temperature, and more. Red Diary finds what repeats across your cycles and explains what's behind it, instead of just recording it. SHARE HOW YOU FEEL Send a phase-aware note to a partner, a friend, or your birth control buddy through iMessage, WhatsApp, or anywhere else. No accounts, on either end. ON YOUR WRIST Cycle day, phase, and progress ring on your watch face in phase-matched colors. Start or end your period, log your mood, and get guidance without reaching for your phone. APPLE HEALTH Steps, calories, exercise, and sleep flow in automatically. See how your energy and activity really shift across your cycle — no extra logging. BIRTH CONTROL REMINDERS Pill, patch, ring, shot, IUD, or implant. On-time reminders, streak tracking, and insights that adapt to your method. WHAT'S PREMIUM Trying to Conceive, Avoid Pregnancy, and Pregnancy modes, Body Weather, full cycle insights, fertility analytics, and mood sharing. Cycle tracking, logging, predictions, calendar, and birth control reminders are free and stay free. Privacy Policy: https://dormeusapps.com/reddiary-privacy.html Terms of Use: https://dormeusapps.com/reddiary-terms.html
Screenshots
Verdict
The clearest difference is monetization model: Red Diary at freemium against Synca's subscription. Red Diary also leads on update cadence (every 3 days vs every 2 weeks) and ratings volume (9 vs 2). On price, rating, review sentiment and ads 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. Synca sells 2 in-app purchases, starting at $4.99 per month and Red Diary sells 2 in-app purchases, starting at $0.99 per month. Whichever you choose, the download price is not the number that matters.
On the App Store both sit at effectively the same score — 5.0 for Synca against 5.0 for Red Diary. Both are backed by a comparable volume of ratings — 2 and 9 respectively. Written reviews split almost evenly too, at 100% and 100% positive.
Synca ships an update every 2 weeks, Red Diary every 3 days. The most recent releases landed on September 29, 2026 and October 1, 2026 respectively.
| Parameter | Synca | Red Diary |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (2 ratings) | 5.0 (9 ratings) |
| Positive reviews | 100.0% of reviews | 100.0% of reviews |
| Number of ratings | 2 | 9 — better |
| Update frequency | Every 2 weeks | Every 3 days — better |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | Subscription | Freemium — better |
| Devices | iPhone | iPhone, Apple Watch — better |
| Requires iOS | 17.0 — better | 17.6 |
| Further details — not scored | ||
| Size | 25 MB | 8 MB |
| Age rating | 4+ | 12+ |
| Developer | Burcu Ibicioglu | RUBINS DORMEUS |
Customer experience
Synca
Red Diary
In-app purchases
Synca
- Synca AI$4.991 Month
- Synca AI7 Days trial$24.991 Year
Red Diary
- Premium Monthly7 Days trial$0.991 Month
- Premium Annual$4.991 Year









