Reviewed by the Solu Editorial Team against NHS, PubMed, and peer-reviewed sources.
The best Flo alternatives are Clue, Natural Cycles, Apple Cycle Tracking, and Solu, each handling your data differently. This guide compares privacy practices, prediction accuracy, and daily guidance so you can choose based on what matters most to you.
The best Flo alternatives are Clue, Natural Cycles, Apple's built-in Cycle Tracking, and Solu, each handling cycle data and prediction differently. Clue leads on research credibility, Natural Cycles is the only FDA-cleared option for contraception, and Solu extends tracking into daily cycle-phase guidance rather than prediction alone.
This article is based on Federal Trade Commission enforcement records, peer-reviewed research on health app data privacy, and NHS guidance on menstrual tracking current as of August 2026.
Why Are Women Looking for Alternatives to Flo?
Flo, formally the Flo Period & Ovulation Tracker, is the most downloaded menstrual cycle app in the world, but its history with user data is what pushes a meaningful number of women toward a different period app. In 2021, the US Federal Trade Commission finalized an order against Flo Health, finding the company had shared sensitive health data, including when a user was trying to get pregnant, with Facebook, Google, and other marketing and analytics firms despite promising to keep that data private. A 2025 qualitative study in Oxford Open Digital Health found that women using cycle tracking apps frequently reported not trusting the app with sensitive information, yet continued using it anyway because the day-to-day benefit still outweighed the stated privacy worry. Women who have switched trackers after a privacy scare often report reading a privacy policy in full for the first time only after deciding to leave, rather than before first signing up.
How Do the Leading Flo Alternatives Actually Compare?
Each major alternative to Flo solves the same basic problem, tracking a menstrual cycle, in a different way. Clue has built its reputation on research partnerships, working with institutions including the University of Oxford, Kinsey Institute, and Johns Hopkins University to study menstrual health at population scale. Natural Cycles built its product around a single physiological signal, basal body temperature, precise enough that it became the first FDA-cleared birth control app. Apple's built-in Cycle Tracking relies on retrospective logging synced across an iPhone and Apple Watch, with no separate account required. Solu takes a different approach again, using a woman's logged cycle phase to time movement and nutrition recommendations for that specific day, turning her data into a same-day plan rather than a static log of dates. For a fuller side-by-side on prediction accuracy across these tools, see the companion guide to the best period tracker app.
Is Natural Cycles a Safer Flo Alternative for Birth Control Specifically?
Most period trackers, including Flo, Clue, and Apple's Cycle Tracking, are not designed or cleared for contraceptive use. Natural Cycles is the exception: its algorithm holds multiple FDA clearances, with published effectiveness of 98% with perfect use and 93% with typical use, a range comparable to combined oral contraceptive pills. That distinction matters for anyone specifically leaving Flo to use an alternative as birth control rather than simply to track a monthly cycle, since general cycle awareness and contraceptive-grade accuracy are not the same claim.
Which Flo Alternative Gives You More Than Just Predictions?
A 2025 content analysis in the Journal of Medical Internet Research reviewing several major reproductive health apps found that most tools still center almost entirely on prediction and logging, with comparatively little app functionality dedicated to acting on what a woman has already recorded. Solu pairs logged cycle phase with a woman's own sleep and recovery data to flag when late-luteal fatigue is likely, rather than only marking a date on a calendar and leaving the interpretation to her. Before switching trackers, it helps to check a short list of practical points:
- Is the privacy policy written in plain language, not just dense legal text?
- Does the app require an account or email address to function at all?
- Can you export or fully delete your data if you decide to leave?
- Is it FDA-cleared, if you plan to use it for contraception?
- Does it offer any guidance beyond a predicted date, such as symptom or phase-based recommendations?
How Do You Choose the Right Flo Alternative for Your Needs?
The right Flo alternative depends on what specifically pushed a woman to look for one. Someone motivated purely by a privacy concern should weigh each app's data practices first, using the FTC record and app-specific privacy policy as a starting point rather than marketing copy. Someone asking "is there a period tracker that doesn't sell my data" is really asking a data-practices question, not an accuracy question, and the two should be researched separately. For a broader comparison across accuracy, privacy, and features together, see the guide to the best app for menstrual health, and for a closer look at what these apps actually do day to day beyond prediction, see what a period tracking app actually does.
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