How do I start tracking my cycle?
When you first open Crimson, you'll go through a brief onboarding to set your average cycle length and last period start date. After that, simply tap the "+" button to log your period days, symptoms, and moods. Predictions improve as you log more cycles.
Is my data stored securely?
Yes. Your data is securely synced to the cloud and protected. We never sell or share your personal health data.
Do I need to create an account?
Yes, an account is required to use Crimson. Sign-up is quick and free. Your account enables secure cloud sync so your data is backed up and accessible across devices. All core features — tracking, predictions, AI insights — are included at no cost.
How does the AI assistant work?
The AI chat feature uses your cycle data (current phase, recent symptoms, tracking history) to provide personalized responses. It can answer questions about your cycle, explain symptoms, and offer wellness suggestions. It works out of the box — no setup or API key needed. Advanced users can optionally use their own OpenRouter API key in Settings.
How accurate are the predictions?
Crimson uses weighted moving averages that factor in your recent cycles more heavily than older ones. The more cycles you track, the more accurate predictions become. For most users, predictions stabilize after 3–4 tracked cycles.
Can I export my data?
Your data is stored in standard formats and accessible through the app. We're working on a full data export feature for an upcoming release.
The app isn't working correctly. What should I do?
Try closing and reopening the app. If the issue persists, ensure you're running the latest version from the App Store or Google Play. For persistent problems, contact us using the button below with a description of the issue.
What makes Crimson different from other period trackers?
Crimson is built with privacy-first design, meaning your health data is securely synced to the cloud and never sold or shared with third parties. Unlike Flo, Clue, and other popular trackers, Crimson does not collect data for advertising. It also includes a built-in AI assistant that understands your current cycle phase and symptom history, and supports four distinct tracking modes: regular cycle tracking, trying to conceive, pregnancy, and perimenopause.
Is Crimson free?
Crimson's core features are free forever — period and symptom logging, calendar, predictions, cycle phase detection, all four tracking modes, and the AI assistant with a daily message allowance. Crimson Pro (monthly or annual) unlocks unlimited AI chat, symptom patterns and correlations, and doctor-ready PDF reports. Every new account starts with a 14-day Pro trial. There are no ads, and exporting your own data as CSV is always free.
Does Crimson work for irregular periods?
Yes. Crimson uses weighted moving averages that give more importance to your recent cycles. If your cycles vary in length, predictions adapt accordingly. The app also calculates a regularity score so you can see how consistent your cycles are over time. For very irregular cycles, predictions become more accurate after 4–6 logged cycles.
Can I use Crimson to track fertility and ovulation?
Yes. Crimson has a dedicated "Trying to Conceive" mode that calculates your fertile window and estimated ovulation day based on your cycle history. It uses your logged data to identify the most likely fertile days and adjusts predictions as more cycles are recorded. The AI assistant also provides fertility-specific insights in this mode.
Does Crimson have a pregnancy tracking mode?
Yes. Crimson includes a full pregnancy mode with weekly development updates, appointment tracking, kick counting, contraction timing, and weight logging. The AI assistant switches to pregnancy-specific guidance, and all pregnancy data is securely stored in the cloud alongside your cycle data.
Can Crimson track perimenopause symptoms?
Yes. Crimson has a dedicated perimenopause mode that tracks hot flashes (frequency, severity, triggers), hormone test results, and irregular cycle patterns. It computes daily and weekly symptom counts and average severity, helping you and your healthcare provider identify trends over time.
How does Crimson protect my reproductive health data?
Crimson securely syncs your health data to the cloud with robust access controls. Only you can access your records. Crimson never sells health data, never shares it with advertisers, and does not build advertising profiles.
Can I share my cycle data with my partner?
Yes. Crimson has a partner sharing feature that lets you generate a share code. Your partner can see selected information like your current cycle phase, predicted periods, and fertility window. You control exactly what data is shared through granular permission settings (phase, predictions, symptoms).
Can I get a report for my doctor?
Yes. Crimson can generate PDF cycle reports and pregnancy reports with date filtering. You can also export your data as CSV. These reports include cycle history, logged symptoms, mood patterns, and predictions — useful for sharing with healthcare providers at appointments.
What symptoms can I track in Crimson?
Crimson supports 44 symptoms across multiple categories including: flow (light, medium, heavy, spotting), pain (cramps, headache, backache, breast tenderness), mood (happy, anxious, irritable, calm, sad), energy levels, sleep quality, digestion, skin changes, and more. You can log multiple symptoms per day along with notes.