🩸Flo: building a $billion dollar health app

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​​The most popular women’s health app in the world was built by two brothers who grew up on a potato farm in Belarus.

It was their third attempt at a women’s health app. When they finally launched, the market was already dominated by a PayPal co-founder backed by $20M+ from Founders Fund and a16z.

The app is Flo, a women’s health app downloaded 420M+ times by women around the world to track periods, ovulation, and pregnancy. It’s a femtech unicorn with $200M+ in annual revenue.

Here’s their playbook.

A word from our partner

You'll read below how Flo won by deeply understanding what women actually want. Turns out, Flo uses Listen Labs to do exactly that.

Listen Labs is an AI-powered customer research platform backed by Sequoia and Ribbit Capital. Their AI interviewer talks to thousands of real people simultaneously, asks follow-up questions like a great researcher would, and turns those conversations into executive-ready reports, highlight reels, and slide decks. Results in hours, not weeks. At a fraction of the cost.

Microsoft, Canva, Sweetgreen, and Flo all use Listen to test ads, validate product concepts, and understand what drives conversion.

Dmitry and Yuri Gurski grew up in Belarus. Their mother was a librarian. She raised them alone. The brothers picked mushrooms and grew potatoes to earn what they could.

Dmitry never got a formal CS education. He taught himself to code. Between the ages of 18 and 22, he wrote five books on computer science and programming. Then, he founded a publishing house called Ideanomix, which at its peak, managed roughly 2,500 educational titles. Yuri was the technical half. He became VP at Mail.ru, one of the largest internet companies in Eastern Europe.

Together, the two brothers started Palta, a startup studio out of Eastern Europe. Palta's portfolio includes AIMatter (acquired by Google), Wannaby (acquired by Farfetch), and the fasting app Simple. The Gurski brothers are serial builders. Flo was not their first rodeo.

For most of their wins, they follow the same framework.

Success = picking a massive and fragmented market + right timing + differentiated product strategy and team

1/ Market 

They picked women’s health because it was enormous and largely overlooked. Most app developers were men. Most VCs were men. They were, in Dmitry’s words, “completely oblivious” to the opportunity right in front of them. 

Women control 80% of healthcare spending decisions in the US, yet femtech received just 2.5% of US healthcare funding in the first half of 2024. A massive market with few serious players. The biggest player at the time was Glow, founded by Max Levchin (PayPal cofounder).

2/ Timing 

A major unlock was that when they launched in 2015/2016, Apple announced that subscription pricing would expand to all app categories, including games, productivity, and utility apps. This enabled apps to monetize beyond ads, significantly improving the monetization potential of a consumer app.

3/ Differentiation 

Most incumbents were building apps that offered surface-level information and tools. Dmitry and Yuri realized the best way to stand out was to focus on education and personalized insights. They envisioned a platform that would empower women with accurate, tailored guidance throughout their reproductive journey.

Their first crack at women's health was an app called Only Women. It flopped due to its complicated interface. Flo was launched in October 2015, 11 years after Only Women.

Having learned from that lesson, they kept the first MVP dead simple. Users could use the app to track their period and see cycle predictions.

One decision they made early was unusual for a startup with almost no users. They set up a medical advisory board before they had meaningful traction. They also brought in Dr. Anna Klepchukova as Chief Medical Officer in 2018.

Within one month of launching Flo, the team immediately realized they were onto something really special.

They saw something pretty unique in their health app: amazing retention. About 40–50% of users were still around after a few months, with only 1–2% churn after that.

They attributed this to the use case, rather than the product itself. The perfect gym fitness app would have terrible retention because people lose motivation quickly, which is precisely why most gyms grossly oversell their memberships knowing only 10% of people would ever show up after the first month.

However, there is built-in retention for Flo since women cannot skip their period.

As the app has evolved, the core functionality remains largely the same.

Dmitry believes that the biggest reason why their first two attempts at a women’s health app failed was because they were too complicated. He emphasized in many of his previous podcast appearances that simplicity is THE MOST IMPORTANT thing for consumer apps.

Simplicity is also the feature that Flo users value the most, according to a company survey. The number two answer is accuracy of predictions.

Dmitry believes simplicity is a core reason why they were able to beat the biggest incumbent at the time, Glow, a well-funded startup started by PayPal cofounder Max Levchin.

Simplicity is such a core belief that Dmitry thinks you should delete features more often than you add them.

Let’s say you launch a feature, and it shows impact. As time goes by, your team builds 20 more features. Competition and cannibalization between features intensifies. That original feature, which was useful a year ago, is now just complexity. It distracts users from better features.

He compares it to bringing an old dog to the vet. "For a product person, to kill old features is almost as sad as bringing your old dog to the vet. You know it's time. But you don't want to do it."

One example is that Flo had a basal temperature feature. Measuring your temperature each morning to predict fertility. He checked the data. Only 0.1% of users used it. They killed it. A fierce wave of negative reviews and support emails followed. If they hadn't checked the data first, they would have concluded it was a disaster. But it was just 0.1%.

Ignore the vocal minority. Focus on features for the mass audience.

The period tracker got Flo to product-market fit, but it wasn't enough to build a business on. Too many competitors offered free tracking. Monetizing the core feature alone was nearly impossible.

To create more value, Flo started building a health superapp.

AI-driven personalized health insights based on each user's logged data. A pregnancy mode that launched in 2017. An anonymous community called Secret Chats where women could discuss intimate health topics without judgment. Some users downloaded Flo just for that feature alone. Health reports that showed visual correlations between symptoms and cycle phases. In October 2023, Flo for Partners, which let users share their cycle data with a significant other.

The app expanded to cover the entire reproductive lifecycle. Teens. Cycle tracking. Trying to conceive. Pregnancy. Early motherhood. Menopause. A single product that could serve a woman for decades.

Still, despite the additional features, the core functionality largely remains simple and straightforward.

Flo's early growth was entirely organic.

The app store algorithms made a huge impact in the beginning, but only because users kept coming back. Strong retention meant the algorithms surfaced Flo to more women searching for period trackers. They would rank high for keywords like “period tracker”.

However, word of mouth was still the main driver. Most women would learn about Flo from their sisters, cousins, and friends.

By August 2017, less than two years after launch, Flo had 10 million monthly active users across 200+ countries. It was adding roughly 1 million new monthly users every month.

The funding was still modest. A $1M seed round in December 2016. A $5M Series A in August 2017, led by Flint Capital with participation from Natalia Vodianova, the Russian supermodel and mother of five.

Vodianova took a board seat and launched an awareness campaign called "Let's Talk About It. Period." She gave Flo credibility, press, and access to audiences the founders couldn't reach on their own.

Beyond word of mouth and product quality, three specific tactics stand out.

Content as acquisition. The Gurski brothers' publishing background turned out to be their unfair advantage. Dmitry spent years publishing content on the internet. Yuri could build the technology to distribute it. They applied that discipline to Flo and built the Flo Health Library. Over 100 medically reviewed articles covering everything from puberty to menopause. Nine free online calculators for due dates, ovulation windows, and other common searches. All optimized for search. Now, millions of monthly visitors show up to the Flo website, all funneling into app download.

Selling fear, not features. Binh Dang, Flo's Head of ASO, revealed the company's core marketing trigger in a late 2025 interview: fear. The kind that brings them in. Flo stopped advertising "period tracking" and "pregnancy monitoring." Those are features. Nobody wakes up excited about tracking their period. Instead, they started talking about planning your days around your cycle. Knowing when you have the best chance to conceive. Understanding why your body feels the way it does.

The Pass It On campaign. In October 2022, Flo launched the Pass It On Project. They gave free Flo Premium subscriptions to women in 22 countries where access to health education is limited. By December 2023, they expanded to 66 countries. Today, 28 million women across 58 countries have free access. This is a growth play because it builds brand quality in fast-growing markets and creates a massive funnel for eventual paid conversion.

For a long time, the Flo team made the same mistake many consumer apps make. They assumed a great product would sell itself. It didn’t.

The team had to go through a fundamental mindset shift, from building features to selling the value of those features.

They started actively explaining why the premium experience was worth paying for. They ran A/B test after A/B test on their paywall, their pricing, their messaging. The result was an 800% increase in premium conversion rates.

This monetization engine paired with a strong retention curve leads to a formidable cash machine.

Close to 25% of Flo’s revenue today comes from users who have used Flo for three years or more.

Some high-level stats on Flo today:

1/ You can build for a pain point you have never experienced. Two men from Belarus built the world’s most popular women’s health app. Still, they had deep market knowledge and over a decade of startup experience that prepared them for this moment.

2/ Retention is more about the use case than the product. You can build the perfect gym app. It will still have terrible retention because gyms have terrible retention. Flo's strong retention is mostly the result of the fact that women can’t skip their period. Before you optimize UX flows, ask whether the underlying behavior is naturally recurring.

3/ Simplicity trumps features…every time. The Gurski brothers’ first two women’s health apps failed because they were too sophisticated. The version that won was the simplest. In fact, you can even boost revenue by deleting features.

4/ Your unfair advantage might come from a past life. Dmitry and Yuri spent a decade in book publishing before touching an app. That background became Flo's growth engine. They built a health content library that drives millions of monthly visitors to the website, all funneling into app downloads. The skill that seems irrelevant to your startup might be the one that makes it work.

5/ Don't assume strong monetization based on a great product. The Flo team assumed a great product would sell itself. It didn't. They had to learn how to explain value, not just create it. Through hundreds of A/B tests, they increased premium conversion 800%. Even Apple doesn't hand you an iPhone in a gray box. How you present value matters as much as the value itself.

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See you next Tuesday!

Leo

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