Engineering Manager - Data Science Team
Appcast · London, England ·
500M+ downloads. 80M+ monthly users. A decade of building – and we're still accelerating. 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, we became the first product of our kind to reach a $1B valuation in 2024 – and we're not slowing down.
With 7M 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 our users know their body better.
The jobWe're hiring a Data Science Lead in London to build and lead our Predictive Growth Optimisation team – pioneering ML models that power our user acquisition strategy, predict lifetime value, and optimise our $25M+ annual marketing spend across channels.
This role owns the strategy, development, and continuous improvement of Flo's pLTV system - a mission-critical model reused across UA, AdTech, personalisation, and financial forecasting. That is the core of the role. Alongside it, you'll stand up a Marketing Mix Modeling (MMM) capability to measure cross-channel effectiveness and inform budget allocation, and develop the algorithms to drive real-time UA campaign management.
You'll lead a team building production systems that directly impact our growth trajectory, staying as hands-on as you choose. What you'll doLead & develop a team of 6+ ML and Backend engineers - hiring, mentoring, and setting technical directionOwn pLTV strategy - architect and evolve our core predictive lifetime value models that inform millions in UA decisionsStand up MMM - build our Marketing Mix Modeling capability: adstock and saturation modelling, channel contribution, and budget allocation, calibrated against our incrementality experimentsPower real-time campaign management - develop the algorithms that optimise our UA campaigns across channels in real timeBuild production ML systems - from real-time prediction services handling millions of daily predictions to MMM modelsDrive cross-functional impact - partner with Growth, Product, and Finance to translate business problems into ML solutionsShape technical architecture - guide MLOps infrastructure, monitoring, and rapid iteration cyclesStay as hands-on as you choose - modeling, architecture decisions, technical problem-solving; your call how deep you go.
What you bringTechnical Leadership7+ years applied ML experience building and deploying models in production4+ years managing technical teams (ML engineers, data scientists, or similar)Expert knowledge of ML fundamentals: supervised/unsupervised learning, time series; strong grounding in causal inferenceExperience with modern ML frameworks (TensorFlow, scikit-learn, CatBoost)Growth & Product ExperienceExperience with growth analytics, attribution modeling, or marketing effectivenessUnderstanding of user acquisition funnels and retention optimizationComfortable translating business requirements into technical roadmapsStrong communication skills - can explain complex models to executive stakeholdersProduction ML SystemsExperience deploying ML models at scaleKnowledge of MLOps practices: model versioning, monitoring, automated retrainingUnderstanding of data engineering fundamentals and cloud platformsNice to haveHands-on experience building Marketing Mix Models end to end, Bayesian or regression basedBackground in consumer tech, mobile apps, or health techKnowledge of privacy-preserving ML techniques and A/B testing methodologyHow we workWe'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 their work seriously, not themselves.
It takes commitment, resilience, and the drive to keep going when things get tough. Because better health outcomes are worth it. What you'll getWe support impact with meaningful reward. Here's what that looks like: Competitive salary and annual reviewsOpportunity to participate in Flo's performance incentive schemePaid holiday, sick leave, and female health leaveEnhanced parental leave and pay for maternity, paternity, same-sex and adoptive parentsAccelerated professional growth through world-changing work and learning supportIn-person collaboration and work in a hybrid model, with 3 days per week spent in the office5-week fully paid sabbatical at 5-year FloversaryFlo Premium for friends & family, plus more health, pension and wellbeing perksDiversity, equity and inclusionOur 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.