Flo is the world’s #1 health & fitness app worldwide on a mission to build a better future for female health. Backed by a $200M investment led by General Atlantic, Flo became the first product of its kind to reach a $1B valuation in 2024. With 6M paid subscribers and the highest-rated experience in the App Store’s health category, Flo has spent 10 years earning trust at scale. The company is building the next generation of digital health – AI-powered, privacy-first, clinically backed – to help users better understand their bodies.

We are hiring a Data Science Lead in London to build and lead our Predictive Growth Optimization team, pioneering ML models that power user acquisition strategy, predict lifetime value, and optimize the $25M+ annual marketing spend across channels. This role owns the strategy, development, and continuous improvement of Flo's predictive lifetime value (pLTV) system, a mission-critical model reused across UA, AdTech, personalization, and financial forecasting. The role balances hands-on technical leadership with people management and builds production systems that impact growth trajectory.

Lead and develop a team of 4+ ML and Backend engineers including hiring, mentoring, and setting technical direction. Own pLTV strategy by architecting and evolving predictive lifetime value models that inform millions in user acquisition decisions. Build production ML systems such as MMM algorithms and real-time forecasting models handling millions of daily predictions. Drive cross-functional impact by partnering with Growth, Product, and Finance teams to translate business problems into ML solutions. Shape technical architecture by guiding MLOps infrastructure, monitoring, and iteration cycles. Stay hands-on by contributing to modeling, architecture decisions, and technical problem-solving as needed.

Technical Leadership: 7+ years of applied ML experience building and deploying models in production, 4+ years managing technical teams including ML engineers and data scientists. Expert knowledge of ML fundamentals including supervised/unsupervised learning, time series, and causal inference. Experience with ML frameworks such as PyTorch, TensorFlow, scikit-learn, and CatBoost.

Growth and Product Experience: Experience with growth analytics, attribution modeling, or marketing effectiveness; understanding of user acquisition funnels and retention optimization; ability to translate business requirements into technical roadmaps; strong communication skills to explain complex models to executive stakeholders.

Production ML Systems: Experience deploying ML models at scale (millions+ predictions/day), knowledge of MLOps practices including model versioning, monitoring, and automated retraining; understanding of data engineering fundamentals and cloud platforms.

Nice to have: Experience with Marketing Mix Modeling, attribution, or ad tech. Background in consumer tech, mobile apps, or health tech. Knowledge of privacy-preserving ML techniques and A/B testing methodology.

Flo is a mission-led, product-driven team that moves fast, stays focused, and takes ownership. The company values commitment, resilience, and a drive to achieve better health outcomes. Benefits include competitive salary with annual reviews, performance incentives, paid holiday and health leave including female health leave, enhanced parental leave for all parents, accelerated professional growth opportunities, flexible office and home working arrangements, a 5-week fully paid sabbatical after 5 years, Flo Premium for friends and family, and additional health, pension, and wellbeing perks. Flo is an equal opportunity employer committed to diversity, equity, and inclusion.