400M+ downloads. 75M+ monthly users. A decade of building – and we’re still accelerating.
Flo is the world’s #1 health app for people who menstruate. Backed by a $200M investment led by General Atlantic, we became the first product of our kind to reach unicorn status – and we’re not slowing down.
With 6M paid subscribers and the highest-rated experience in the App Store’s health category, we’ve spent 10 years earning trust at scale. Now, we’re building the next generation of digital health – AI-powered, privacy-first, clinically backed – to help everyone who menstruates know their body better.
The Job
Build systems that power the #1 Health App for Women
We’re not a startup guessing what might work anymore, we’re operating at serious scale. Flo is used by 1 in 4 women aged 18–44 in the US. And we just hit our biggest month ever with 8.6M installs and a 2.8M MAU jump. The engineering behind that? Complex, distributed, secure and yours to help shape.
At Flo, backend engineering is core product work.
We build:
- Data-driven health insights that genuinely change lives
- Distributed systems that stay fast, available and scalable under massive real-time demand
- Privacy-first features like Anonymous Mode - recognised in TIME’s Best Inventions
- Tooling and platforms that help Flo’s teams move faster, with fewer bottlenecks
We’re tech-agnostic when hiring for backend. If you’ve built and run distributed systems and want to work in Scala (or already do), great. We’ll support your ramp-up. What matters most: you can solve problems, own outcomes, and keep learning.
Your Experience
You’ll thrive here if you:
- Have 7+ years’ experience building distributed backend systems
- Know what it takes to make systems fast, reliable and secure and when to prioritise each
- Are fluent in Java, Scala, Python or similar (and curious enough to learn Scala with us)
- Get DevOps, databases (SQL and NoSQL) and love designing APIs that just work
- Have a strong handle on writing clean, documented, version-controlled code
- Take ownership, show initiative and don’t wait to be told
- Are product-minded and always thinking about the end-user impact
Bonus if you’ve worked with:
- Stream processing
- Public cloud infrastructure (AWS, GCP etc.)
What’s in it for you?
You’ll join a senior engineering team that moves fast, thinks big and builds tech used by millions daily. You’ll work on meaningful problems with real impact - in health, privacy and scale. This isn’t just code for the sake of code. This is building the future of personalised health.
#LI-Hybrid #LI-LM12
Salary Range - gross per month
€6.000—€10.500 EUR
We’re a mission-led, product-driven team. We move fast, stay focused and take ownership – from brief to build to impact. Debate is encouraged. Decisions are shared. We care about craft, ship with purpose, and always raise the bar.
You’ll be working with people who take the work seriously, not themselves. And who believe better health for everyone who menstruates is worth building for.
What you’ll get
We support impact with meaningful reward. Here’s what that looks like:
- Flexible hybrid setup – plus up to 2 months a year working abroad
- Competitive salary and annual reviews
- Equity through Flo’s Employee Share Option Plan (ESOP)
- Paid holiday, sick leave, and extra female health leave
- Six months paid maternity and one month paid paternity leave (same-sex and adoptive parents included)
- Growth and learning support
- Unlimited Flo Premium access
- Plus more health, pension and wellbeing perks
Diversity, equity and inclusion
Our strength is in our differences.
At Flo, hiring is based on merit, skill and what you bring to the role – nothing else. We’re proud to be an equal opportunity employer, and we welcome applicants from all backgrounds, communities and identities.
Read our privacy notice for job applicants.
Top Skills
What We Do
Flo is the essential female health partner. We are building a better future for female health by helping women harness the power of their body signals.
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Flo in numbers:
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#1 period tracker in the USA by active audience
#1 most downloaded female health app worldwide
47 million monthly active users
240 million installs
28M women got pregnant while using Flo (the number indicates users who logged pregnancy in app during 2015-2022)
Flo prioritizes safety and keeps a sharp focus on being the most trusted digital source for women's health information.
Flo intensively uses Data Science and AI to deliver the most personalized content and services available.
Flo is currently available in 22 languages on iOS and Android. 55% of users are located in the US and Europe.
We are committed to putting privacy of our users first. Our users trust our technology to keep their sensitive information private and we are responsible for providing a safe and secure platform for them to use. We regularly carry out privacy assessments to monitor risks including data protection impact assessments and third-party risk assessments. In March 2022 Flo completed an external, independent privacy audit which confirmed there are no gaps or weaknesses in our privacy practices.
