Whether you're looking for a Flo alternative, a Clue alternative, a Premom alternative, or your very first period tracker, the right pick depends on what you value most: privacy, accuracy, AI features, fertility support, or price. Below is a detailed comparison of the six most notable period tracking apps available in 2026, based on publicly available features and policies. New to cycle tracking? Start with our period tracking guide, then come back and choose your app.
Feature Comparison
| Feature | Crimson | Flo | Clue | Natural Cycles | Premom | Apple Health |
|---|---|---|---|---|---|---|
| Price | Free tier + optional Pro | Free tier + $49.99/yr Premium | Free tier + $49.99/yr Plus | $99.99/yr or $14.99/mo | Free (built into iOS) | Free + Premium (~$100–150/yr) |
| AI Assistant | Yes (context-aware, knows your phase) | Limited (premium only) | No | No | No | PCOS AI (Premium) |
| Cloud Sync | Yes (secure cloud sync) | Yes | Yes | Yes | iCloud only | Yes |
| Account Required | Yes (free) | Yes | Yes | Yes | No | Yes |
| Data Encryption | Encrypted in transit & at rest | Encrypted at rest | Encrypted at rest | Encrypted at rest | End-to-end encrypted | FTC cited past lapses |
| Data Sold to 3rd Parties | Never | FTC complaint history | No | No | No | FTC order (2023) |
| Symptom Tracking | 70+ symptoms | 50+ symptoms | 40+ symptoms | Limited | Basic | 50+ symptoms |
| Prediction Method | Weighted moving averages | Machine learning | Statistical algorithms | Basal body temperature | Statistical estimates | LH tests + BBT + algorithms |
| Pregnancy Mode | Yes (full tracking) | Yes | Basic | Yes | No | Yes |
| Perimenopause Mode | Yes (hot flashes, hormones) | Yes (added 2025) | Yes | No | No | No |
| Fertility Tracking | Yes (TTC mode) | Premium only | Yes | Yes (FDA-cleared) | Basic | Yes (LH test reader) |
| Partner Sharing | No | Limited | No | Yes | No | Yes (Predad) |
| PDF Reports for Doctor | Yes + CSV export (free) | Premium only | No | Yes | No | Premium only |
| Platforms | iOS, Android | iOS, Android, Web | iOS, Android, Web | iOS, Android | iOS only | iOS, Android, iPad |
Prices and features verified July 2026 from App Store listings and official sites.
App-by-App Breakdown
Crimson — the privacy-first AI tracker
Crimson is a free, AI-powered period and fertility tracker built with a privacy-first architecture. Your health data is securely synced to the cloud and protected with robust access controls. Crimson supports four tracking modes — cycle tracking, trying to conceive, pregnancy, and perimenopause — and includes a context-aware AI assistant that knows your current cycle phase, recent symptoms, and tracking history. The core app is free; an optional Crimson Pro subscription adds unlimited AI, starting with a 14-day free trial.
Strengths
- Genuinely useful free tier: logging, predictions, all four modes, daily AI allowance
- AI works out of the box, no setup or API key needed
- Secure cloud sync with privacy-first design
- AI assistant with cycle-phase awareness
- 70+ tracked symptoms across all categories
- 4 distinct modes including perimenopause
- Data never sold or shared with third parties
- PDF reports and CSV export included free
Limitations
- New app, smaller community
- No web app yet (mobile only)
- Unlimited AI requires Crimson Pro
- No FDA clearance for contraceptive use
Flo — the most popular alternative
Flo is the most downloaded period tracker globally with over 300 million downloads. It offers a comprehensive feature set including period tracking, pregnancy mode, a perimenopause mode launched in 2025, and health articles. The free tier covers basic tracking, while Flo Premium ($49.99/year) unlocks advanced insights, personalized health reports, and AI features. Flo faced an FTC complaint in 2021 for sharing user health data with third parties including Facebook and Google, though the company has since updated its privacy practices. We break down Crimson vs Flo in detail on a separate page.
Strengths
- Largest user base and community
- Extensive health content library
- Web app available
- Pregnancy mode with weekly updates
Limitations
- Many features locked behind Premium subscription
- FTC privacy complaint history
- Account required to use
- Ads in free tier
Clue — the science-backed alternative
Clue is a science-backed period tracker known for its clean, gender-neutral design and partnerships with academic researchers. The free tier includes basic cycle tracking, while Clue Plus ($49.99/year) adds personalized cycle analysis and additional insights. Clue also offers a perimenopause mode. Clue is based in Berlin and subject to GDPR, and has published research in collaboration with Stanford, Columbia, and Oxford universities.
Strengths
- Clean, science-focused design
- Strong research partnerships
- GDPR-compliant (EU-based)
- Gender-neutral interface
Limitations
- No AI assistant
- Account required
- No partner sharing
- Advanced insights require subscription
Natural Cycles — the FDA-cleared alternative
Natural Cycles is the first FDA-cleared birth control app that uses basal body temperature (BBT) readings to determine fertile and non-fertile days. It requires daily temperature measurements, either manually or via a connected thermometer or Apple Watch. The subscription costs $99.99/year or $14.99/month, making it one of the more expensive options.
Strengths
- FDA-cleared for contraceptive use
- Temperature-based (objective data)
- Strong for fertility awareness
- Partner sharing available
Limitations
- Most expensive option ($99.99/yr)
- Requires daily temperature readings
- No AI features
- No perimenopause support
- Limited symptom tracking
Premom — the hardware-connected alternative
Premom is the app arm of the Easy@Home test-strip brand, built for couples trying to conceive. Its standout feature is a camera-based ovulation test reader that quantifies LH strips, alongside auto-syncing BBT thermometers, a PCOS-focused AI, partner linking (Predad), and a large community with expert consultations. In 2023 the FTC barred Premom from sharing users' health data for advertising after finding it disclosed sensitive health data to AppsFlyer, Google, and two China-based analytics firms without consent; the settlement included a $100,000 civil penalty.
Strengths
- Camera-based LH test reader (quantifies strips)
- Auto-syncing BBT thermometer ecosystem
- Large TTC community and expert consultations
- Partner sharing (Predad)
Limitations
- 2023 FTC order for sharing health data without consent
- Best features require their hardware (strips, thermometer)
- Premium is pricey (~$100–150/yr)
- TTC-focused; no perimenopause mode
Apple Health Cycle Tracking — the built-in alternative
Apple Health Cycle Tracking is built into iOS and integrates with Apple Watch for automatic wrist temperature data. It provides basic period and fertility predictions using on-device processing, which is strong for privacy. However, it offers limited symptom tracking, no AI features, and is only available within the Apple ecosystem.
Strengths
- Built into iOS (no extra app needed)
- On-device processing (strong privacy)
- Apple Watch wrist temperature integration
- Free
Limitations
- iOS/Apple Watch only
- Very basic symptom tracking
- No AI assistant
- No pregnancy or perimenopause mode
- No partner sharing or doctor reports
Privacy Comparison
After the Dobbs v. Jackson decision in 2022, period tracker privacy became a serious concern for many users. If that's what brought you here, our private period tracker guide goes deeper on what to look for. Here's how each app handles your most sensitive health data:
| Privacy Feature | Crimson | Flo | Clue | Natural Cycles | Premom | Apple Health |
|---|---|---|---|---|---|---|
| Free account | Yes | Free tier + paid | Free tier + paid | Paid only | No account needed | Free tier + paid |
| Secure cloud sync | Yes | Yes | Yes | Yes | iCloud only | Yes |
| Data encrypted in transit | Yes | Yes | Yes | Yes | Yes | Yes |
| No 3rd-party data sharing | Never | Updated post-FTC | No | No | No | FTC order (2023) |
| Data deletion available | Yes (instant) | Yes | Yes | Yes | Yes | Yes |
| GDPR compliant | Yes | Yes | Yes (EU-based) | Yes (EU-based) | Yes | US-based |
Which App Is Right for You?
Quick answers to the questions we hear most. For the full picture, read the app-by-app breakdown above.
What is the most private period tracker?
Crimson is built privacy-first: your data is encrypted in transit and at rest, it's never sold or shared with third parties, and you can delete your account and data instantly from the app. Apple Health is another strong option since its processing happens on your device. Our private period tracker guide covers what to look for before you trust any app with cycle data.
Is Flo safe to use?
Flo is the most downloaded period tracker in the world, but it settled an FTC complaint in 2021 after sharing users' health data with third parties, including Facebook and Google. The settlement requires Flo to get explicit consent before sharing health data and to submit to independent privacy reviews, and the company says it has overhauled its practices since. Read the FTC's release and decide where your comfort level is.
What is the best Flo alternative?
Crimson is the strongest Flo alternative if privacy and a free AI assistant matter to you. It never sells your data, it runs on iOS and Android, and it covers cycle tracking, trying to conceive, pregnancy, and perimenopause in one app. If you prefer a science-first, gender-neutral design, Clue is the next best alternative.
Which period tracker has the best free tier?
Crimson's free tier includes period logging, predictions, all four tracking modes, 70+ symptoms, PDF reports and CSV export, and a daily AI allowance. No subscription required. The optional Crimson Pro subscription adds unlimited AI, starting with a 14-day free trial. Apple Health is also completely free, but it only covers basic tracking on iOS.
Which app is best for trying to conceive?
For contraception based on fertility awareness, Natural Cycles is the only FDA-cleared app. For getting pregnant, Crimson's trying-to-conceive mode tracks your fertile window and ovulation alongside your symptoms, and it's free. Our ovulation calculator can give you a quick estimate before you download anything. Whatever you use, no app replaces medical advice, so talk to your doctor about fertility concerns.
Try Crimson free
Core tracking is free, no subscription required. Pro starts with a 14-day trial. Your data stays yours.
Download on the App Store