Clue is a period and cycle tracking app I've been using for years. It's not just a simple calendar; it's a comprehensive health companion focused on reproductive and menstrual health. The app was first launched back in 2013 and is available for free download on both the Google Play Store and the Apple App Store. It has millions of installs globally. You don't need to pay to download or install the app, and while it does offer a premium subscription called Clue Plus, the core tracking features are completely free to use. You do need to create an account to use it, which helps sync your data across devices. I've noticed some non-intrusive ads in the free version, but they're easy to ignore.

Using the app is straightforward. You log symptoms, moods, flow intensity, and other factors daily. The more data you put in, the better its predictions become. A great tip is to enable notifications for your predicted period start date and fertile window—it's surprisingly accurate once it learns your patterns. I also use the tags feature a lot to note things like headaches or changes in sleep, which helps me see correlations over time.

Compared to other apps in this genre, like Flo or Period Tracker, I chose Clue because it feels more science-based and less "pink and flowery." The interface is clean, data-driven, and gender-neutral, which I appreciate. While some apps bombard you with community forums and horoscopes, Clue sticks to the health data, making it feel more like a legitimate tool than just a period diary. For someone who wants clear insights without the fluff, this app is a top choice.

• 🔬 Science-Backed Tracking: Clue's approach is developed in collaboration with research institutions. Unlike many apps that just guess, its algorithm for predicting cycles and fertile windows is based on clinical studies, which gives me more confidence in the data.
• 📊 Clean, Data-Focused Interface: The app presents information in clear charts and graphs. You get a visual overview of your cycle phases, symptom patterns, and predictions without any distracting glitter or cute icons, setting it apart from more decorative trackers.
• 🔔 Highly Customizable Notifications: You can set reminders for everything from your predicted period start to taking medication or logging daily info. This level of customization is more granular than what I've found in simpler apps, making it a true daily health habit tracker.
• 🌐 Global & Inclusive Design: The app uses inclusive language and a neutral color scheme. It's designed for anyone who menstruates, not just women, which is a thoughtful and standout feature in this genre of app.

• ✅ Privacy-First: Clue is known for its strong data privacy policy, storing data anonymously. Compared to some popular apps that share data with advertisers, I feel much safer using this app.
• ✅ Prediction Accuracy: After a few cycles of input, its predictions for my period and fertile window have been consistently more reliable than those from apps like Glow or Maya.
• ✅ No Clutter: The interface is minimalist and ad-free in its core functions. Unlike Flo, which has a busy home screen, Clue lets me focus on my data immediately after I open the app.

• ⚠️ Limited Free Insights: While tracking is free, some deeper analysis and health insights are locked behind the Clue Plus subscription. Apps like Spot On offer more educational content for free.
• ⚠️ Less Community Focus: If you're looking for forums or social features to connect with others, Clue doesn't have them. An app like Flo has a massive community, which some users might prefer.
• ⚠️ Steeper Learning Curve: The sheer number of tracking options can be overwhelming at first. Simpler apps like Period Tracker are easier to set up and use immediately.