Comparison

Synca vs Caelyn

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

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.

Highlights
  • 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
Read full description

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

About

Caelyn

This period tracker learns your unique cycle patterns and keeps all your health data private on your device. It offers detailed insights into your cycle, symptoms, and mood, with robust privacy features and an optional Pro version for advanced analytics.

Highlights
  • Personalized cycle learning
  • Detailed symptom and mood logging
  • On-device data storage
  • Privacy-focused design
  • Cycle pattern insights
  • Data export (CSV/PDF)
  • Apple Health integration
Features
Read full description

Your period, your patterns, your phone. Nothing leaves it. Caelyn is a period tracker that learns how your cycle actually works, then keeps everything it learns on your iPhone. There is no account to create and no server of ours holding your health data, because we do not run one. WHERE YOU ARE, EVERY DAY Open the app and you know. Cycle day, the phase you are in, and what is coming next. Your next period, your fertile window, and when PMS is likely to start. Log a period, a mood, a symptom, or nothing at all. Caelyn works with whatever you give it and gets sharper the more you log. Track flow, pain and where it hurts, mood, energy, basal temperature, cervical mucus, ovulation and pregnancy tests, medication, and a private note for anything that does not fit a box. Eleven everyday symptoms are built in, and you can add your own. IT LEARNS YOU, NOT AN AVERAGE Most apps assume everyone ovulates fourteen days before their period. Caelyn watches your own logs and works out your real luteal length, your own PMS window, and the symptoms that tend to arrive before you bleed. After a couple of cycles it starts telling you things you would not spot yourself. Which symptoms show up in which phase. When your energy dips. Whether your cycle is steadier than you thought. Every one of those is worked out on your iPhone, from your data, and it shows you the numbers behind it. IS THIS NORMAL The question everyone actually has. Caelyn answers it with your cycle length, your period length, and your pain against the ranges most people fall into, and it says plainly when something is worth a conversation with a doctor. No judgement, no scare tactics. BUILT SO YOUR DATA CANNOT LEAK Every entry lives in a private database on your iPhone. Caelyn makes no network calls of its own. It has no analytics, no advertising, no third party trackers, and nothing to sell. Lock it behind Face ID or a PIN. Hide the app in the switcher so a glance shows nothing. Turn on private notifications so your lock screen never spells out your cycle. Set a duress PIN that quietly erases everything if you ever need it to. This is not a promise about how we behave. It is how the app is built. There is nothing for anyone to hand over, including us. WHEN YOU NEED TO SHOW SOMEONE Export a CSV whenever you like, and keep it wherever you want. Caelyn Pro adds a clear PDF of your history for an appointment, so you walk in with dates and patterns instead of trying to remember. FREE, AND GENEROUS ABOUT IT Unlimited logging, full predictions, the calendar, reminders, five pattern insights, six months of your year in review, a home screen widget, Apple Health, app lock, and CSV export are all free. They stay free. CAELYN PRO Every pattern Caelyn finds instead of the first five. Charts for cycle length, period length, symptoms, mood, pain and temperature. A full twelve months in review. A PDF for your doctor. Fertility tracking if you are trying to conceive, plus pregnancy and postpartum modes. Modes for PCOS, endometriosis and perimenopause. Your cycle on your Apple Watch and lock screen. Pro is 3.99 a month with a seven day free trial, or 19.99 a year. You can also pay once and own it forever. Whichever you pick, the privacy is identical. We charge for depth of analysis, never for keeping your data safe. A NOTE ON WHAT THIS IS Caelyn is a personal cycle tracker, not a medical device. Predictions are estimates based on what you log, and they will sometimes be wrong. It should not be used as contraception. For anything that worries you, please talk to a doctor or nurse. Made for anyone who wants to understand their body without handing it over. Terms of Use: https://rajeshpanta.github.io/caelyn/terms.html Privacy Policy: https://rajeshpanta.github.io/caelyn/privacy.html

Screenshots

Synca4 screens
Caelyn4 screens

Verdict

The call

The clearest difference is monetization model: Caelyn at freemium against Synca's subscription. Caelyn also leads on update cadence (every 2 days vs every 2 weeks) and device support (3 vs 1). On price, rating, review sentiment and ratings volume 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Synca sells 2 in-app purchases, starting at $4.99 per month and Caelyn sells 3 in-app purchases, starting at $3.99 per month. Whichever you choose, the download price is not the number that matters.

ReceptionRating · Positive reviews · Number of ratings

On the App Store both sit at effectively the same score — 5.0 for Synca against 5.0 for Caelyn. Both are backed by a comparable volume of ratings — 2 and 2 respectively. Written reviews split almost evenly too, at 100% and 100% positive.

UpkeepUpdate frequency

Synca ships an update every 2 weeks, Caelyn every 2 days. The most recent releases landed on October 15, 2026 and October 24, 2026 respectively.

Scorecard3 real differences · 7 level
Synca versus Caelyn: the parameters behind the verdict, then further details
ParameterSyncaCaelyn
PriceFreeFree
Rating5.0 (2 ratings)5.0 (2 ratings)
Positive reviews100.0% of reviews100.0% of reviews
Number of ratings22
Update frequencyEvery 2 weeksEvery 2 days — better
AdsNoNo
In-app purchasesYesYes
MonetizationSubscriptionFreemium — better
DevicesiPhoneiPhone, iPad, Apple Watch — better
Requires iOS17.017.0
Further details — not scored
Size25 MB10 MB
Age rating4+12+
DeveloperBurcu IbiciogluRajesh Panta

Customer experience

Synca

All ratings2 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews1 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

Caelyn

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews1 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

2 purchases

Synca

Subscriptions2
  • Synca AI$4.991 Month
  • Synca AI7 Days trial$24.991 Year
3 purchases

Caelyn

Subscriptions2
  • Pro Monthly7 Days trial$3.991 Month
  • Pro Yearly$19.991 Year
One-time1
  • Pro Lifetime$99.99

Questions

Is Synca free?
Synca is free to download, with in-app purchases available.
Is Caelyn free?
Caelyn is free to download, with in-app purchases available.
Which has better reviews, Synca or Caelyn?
Synca and Caelyn are both rated 5.0 out of 5 on the App Store, from 2 and 2 ratings respectively.
Do Synca or Caelyn have ads?
Neither Synca nor Caelyn shows ads.
Which is updated more often, Synca or Caelyn?
Synca ships an update every 2 weeks, and Caelyn every 2 days. Most recently, Synca was updated on October 15, 2026 and Caelyn on October 24, 2026.

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