Femtech & Cycle Health on HealthKit
Cycle, fertility, and menopause apps stand or fall on two things: HealthKit done correctly, and sensitive data handled like it matters. iOS 27 extends Apple's cycle tracking toward perimenopause and menopause, which opens up the category funded companies like Flo, Midi, Elektra, and Maven are competing in. I build the HealthKit layer and the privacy posture these apps need, with the discretion this data demands.
- HealthKit cycle tracking: menstrual flow, basal body temperature, ovulation tests, and symptoms, read and written correctly with the user's explicit permission
- the perimenopause and menopause tracking Apple is expanding into, a market women over forty have been badly underserved in
- sensitive-data handling for intimate health apps, the area I work in with Silk, where leaking the data is worse than shipping no feature
What clients say
"Vadim was instrumental to the success Epsy enjoyed on iOS, taking it from an idea on a Miro board to the highest rated and most downloaded app of its kind on the store."
James C. · Mobile Engineering Lead, Epsy
"We had a strict deadline, and Vadim managed to complete the job in time. He gave us meaningful feedback and suggested better approaches, not trying to blindly stick to our specification."
Founder · Pre-seed streaming service
"I can say with confidence that it will be difficult to find a better developer. Vadim is achievement-oriented, highly organized, with very good communication skills."
Alex Z. · Co-Founder, eda.so
Related work
Apple's Problem with Bodies
I shipped a wellbeing journal and discovered the App Store still isn't sure whether the human body is health, lifestyle, or sin.
Silk
The health metric your phone doesn't track
Let's have a look at this really powerful toolkit released by Apple during last three years to both make profit and make people's lifes healthier and safer.
Common engagements
Build the HealthKit layer for a cycle or menopause app
I build the HealthKit layer for the cycle and reproductive-health types, and handle the parts teams get wrong: partial permissions, where the user grants some types and denies others, and the fact that you cannot tell a denied type from an empty one. Most cycle apps carry a subtle bug here that quietly corrupts their predictions and never throws an error, which is the worst kind to find in production.
Get the privacy and data handling right
Reproductive-health data is the most sensitive category an app can hold. In some US states the legal exposure now reaches the user whose data it is, which raises the stakes well past your own liability. I build the privacy architecture this data demands: kept where it cannot quietly become someone else's evidence, kept out of your analytics, and labelled to match what your code actually does. For a funded company this is also diligence material, because investors and acquirers ask how you handle this data, and a clean answer is worth money.
Fix or harden an existing femtech app
You already shipped, and now you have a HealthKit sync that drops data, predictions that drift, or a privacy review from an investor you need to pass. I audit what you read and write, find where permission handling or background delivery is failing, and tighten the data handling to the standard this category is held to. Often the prediction model is fine and the data feeding it is the problem, incomplete because of a permissions bug you never saw.
Pricing
Architecture reviews, hiring help, second opinions on that thing that's been bugging you.
Features, MVPs, migrations, firefighting. Minimum 5 days.
Priority support: review agency code, join architecture calls, catch problems before they ship.
Questions
Do we even need HealthKit, or can we store cycle data ourselves?
You can store it yourself, but HealthKit is usually worth it for two reasons. One, users already have cycle data in Health from other apps and the watch, and reading it saves them re-entering months of history. Two, writing back makes your app a good citizen in the user's health record instead of a silo. The trade is that HealthKit's permission model is fiddly, and getting it wrong corrupts your data quietly. That is the part I handle.
How do we handle reproductive data given the legal climate in the US?
Carefully, and with an architecture designed so that what you cannot produce, you cannot be compelled to hand over. The exposure here is real and it lands on your user, which is why several femtech apps quietly re-architected after 2022 and why investors now ask about it directly. The specific design that gets you there depends on your features and your sync model, and it is exactly the decision you want made by someone who has shipped sensitive-health data before, rather than pieced together from blog posts under deadline.
We're a funded startup competing with Flo and Midi. Where does an iOS contractor help?
On the parts that are easy to underestimate and expensive to get wrong: the HealthKit integration, the privacy architecture, the watch and widget surfaces, and the App Review questions a health app draws. Your differentiation is your product and your clinical content, which I do not touch. What I do is make the platform layer solid, so your team spends its time on the product only you can build instead of disappearing into a background-delivery bug that has nothing to do with it.
Is this different from your HealthKit medical work?
Related, but a different track. Medical and clinical apps deal with CareKit, ResearchKit, regulatory paths, and clinician workflows. Consumer femtech is lighter on regulation and heavier on daily-use product, retention, and the privacy stakes around reproductive data. You reuse the HealthKit foundation across both; the obligations and the product design on top of it diverge. I do both, and which track your product sits on is one of the first things worth pinning down, because the two get reviewed and regulated differently.
How quickly can you start?
Advisory calls can happen within days. For project work, I typically need 1-2 weeks notice to clear the calendar, though I keep some buffer for urgent firefighting. Check the availability badges above for current openings.
Do you work with early-stage startups?
Yes, from pre-seed to Series C and beyond. For very early teams, the advisory tier often makes more sense than project work: you get architecture guidance without committing to a large engagement before you've validated the product.
What's included in the day rate?
Everything: code, architecture decisions, code review, documentation, async Slack availability during working hours. No surprise add-ons. I bill for time spent working on your project, not for "thinking about it in the shower."
We're in a different timezone. Will that slow things down?
I'm currently in Vancouver (PST), with full overlap for North American teams. For UK and Europe, I'm online by their afternoon. For Gulf or APAC, we'd agree on overlap hours and handle the rest async. I've worked with teams from San Francisco to Dubai.
Areas I cover
Where I've worked CV LinkedIn
Building a femtech or cycle-health app?
Tell me what you're working on. I reply within 48 hours.
work@drobinin.com