Clue, founded by Danish entrepreneur Ida Tin in 2012, is the most widely used period tracking app founded by a woman. Natural Cycles, co-founded by physicist Elina Berglund, is another prominent woman-led fertility app built around an FDA-cleared algorithm.
Clue, founded by Danish entrepreneur Ida Tin in 2012, is the most widely used period tracking app founded by a woman, with more than 10 million users worldwide. Natural Cycles, a fertility awareness app and cycle tracker co-founded by physicist Elina Berglund in 2013, is another prominent woman-led option, built around an FDA-cleared algorithm rather than a simple calendar estimate.
This article is based on public company records and verified reporting from Forbes and The Bureau of Investigative Journalism, alongside PubMed-indexed research on period app data privacy current as of July 2026.
Which Period Tracking Apps Were Founded by a Woman?
Two period and cycle tracking apps stand out for being founded or co-founded by a woman: Clue and Natural Cycles. Clue was built by Ida Tin, who launched the app in 2012 and later coined the term "femtech" to describe technology built around female biology. Natural Cycles was co-founded in 2013 by Elina Berglund, a particle physicist who had worked on the team that discovered the Higgs boson at CERN, alongside her husband Raoul Scherwitzl. Both apps sit in contrast to Flo, currently one of the most downloaded period trackers worldwide, which was founded by two brothers with no clinical or reproductive health background at the time of launch, a detail covered further in the guide to the top health and fitness apps for women.
Who Is Ida Tin and Why Did She Build Clue?
Ida Tin built Clue after growing frustrated with the side effects of her own hormonal birth control and finding no app that tracked cycles with real scientific rigour. According to Forbes, Tin built Clue's early data practices around research partnerships with universities rather than advertising, a decision that has shaped how the company still handles user data today. Solu maps daily movement, nutrition, sleep, and energy guidance to the user's current cycle phase, a design approach that, like Clue's founding motivation, starts from a woman's lived cycle experience rather than a generic health calendar.
How Is Natural Cycles Different From Clue?
Natural Cycles functions as a certified method of contraception, not just a period tracker, using an algorithm that combines daily basal body temperature readings with cycle data to indicate fertile and non-fertile days. A 2025 Forbes feature on the rise of hormone-free birth control confirmed the app remains an FDA-cleared algorithm-based contraceptive method classified as a medical device. This distinguishes it from calendar-based cycle trackers, and from apps that estimate rather than clinically indicate fertility, a difference explained further in the guide to how fertility apps actually work.
Does the Founder's Gender Affect a Period App's Privacy or Accuracy?
Founder gender alone does not guarantee a safer or more accurate app, but it has shaped which design and privacy failures have come to light over time. A 2025 lawsuit covered by The Bureau of Investigative Journalism found that Meta had intercepted sensitive menstrual and reproductive health data from Flo through embedded third-party tracking software, despite the app's own privacy assurances, resulting in a jury ruling that Meta violated California's privacy law. Questions like which period app is safest for your data or is Flo actually private tend to matter more in practice than who built the app, though founder background often correlates with how seriously a company treats that question from the start. Solu takes a different practical approach by keeping cycle, sleep, and nutrition guidance tied directly to the user's own logged data rather than monetising it through third-party advertising partnerships.
What Do Privacy Studies Actually Say About Period Tracking Apps?
Independent research on period app privacy paints a consistent picture of user unease. A 2025 qualitative study published in PMC, interviewing 25 women aged 19 to 38 about their period tracking app habits, found that users felt powerless and uninformed about how to mitigate privacy risks despite expressing significant concern about data access by employers, insurers, and law enforcement. Women who compare an app's actual privacy policy against its marketing claims, rather than assuming a period tracker is safe by default, often notice a gap between the two that only becomes obvious on close reading. This is a large part of why the guide to whether period tracking apps are 100% accurate is worth reading alongside any privacy comparison, since accuracy and privacy are separate questions that get conflated in most app store reviews.
What Should You Actually Look for in a Period Tracking App?
Choosing a period tracking app on founder identity alone overlooks several factors that matter more day to day. The following checklist covers what is worth confirming before committing months of logged health data to any single app:
- Who built the app and what motivated its founding
- Whether the privacy policy names specific third parties data is shared with
- Whether predictions come from a validated algorithm or a simple calendar average
- Whether the app is free, subscription-based, or monetised through advertising
- Whether the app links cycle data to other health signals like sleep, nutrition, or movement
The bottom line: Clue and Natural Cycles are the clearest examples of period and fertility apps founded or co-founded by a woman, but privacy policy, algorithm quality, and data-sharing practices matter more for day-to-day trust than founder identity alone.
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