Crimson: Cycle & Fertility
AI Period & Fertility Tracker
About
An AI-powered application that helps users track their menstrual cycles, predict fertile windows, and gain personalized insights into their health. It offers smart cycle tracking, AI-driven analysis of symptoms and moods, and detailed predictions with a focus on user privacy.
What's New in Crimson
1.0.12
August 28, 2026
Reminders now ask for permission when you finish onboarding, so period and ovulation alerts actually fire. Customize your dashboard — hide and reorder cards — without repeating the same countdowns. Pregnancy week milestones announce on the right day.
MoreSubscription plans
Crimson Pro (Annual)
All features. Save 52% vs monthly.
FAQ
How does Crimson use AI to track cycles?
Crimson utilizes AI analysis to process your logged periods, symptoms, moods, and health data. This allows for automatic cycle length calculation, prediction of fertile windows and ovulation, and generation of personalized insights tailored to your current cycle phase.
Is Crimson free to use?
The core features of Crimson, including tracking and basic insights, are available for free. For advanced analytics and features, a subscription to Crimson Pro is available, with monthly and annual plans.
What are the subscription options for Crimson Pro?
Crimson Pro offers two subscription tiers: a monthly plan for $6.99 and an annual plan for $39.99. These plans unlock advanced features and deeper insights into your cycle.
Does Crimson work offline?
Yes, Crimson is designed with privacy first and works offline with local data storage. Optional cloud sync with end-to-end encryption is available for data backup and access across devices.
How accurate are Crimson's predictions?
Crimson uses weighted moving average predictions that improve over time as you log more data. It also provides cycle regularity scoring and phase detection for a comprehensive understanding of your cycle patterns.
What devices does Crimson support?
Crimson is available on iPhone, iPad, and iPod. It features a clean, intuitive interface with support for both dark and light modes.
When was Crimson last updated?
The latest version of Crimson, 1.0.3, was last updated on August 1, 2026. The app was initially released on July 27, 2026.
What is the age rating for Crimson?
Crimson has an age rating of 12+, making it suitable for teenagers and adults. The app focuses on providing health information and tracking for users.