iOS Engineer I - Subscriptions

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 job As Senior Product Manager for Predictive Growth at Flo, you'll own Flo's predicted Lifetime Value (pLTV) platform across iOS, Android, and Web. pLTV is the shared signal behind UA bidding, budget allocation, creative-testing prioritisation, finance forecasting, and roadmap decisions across the organisation — making it one of the highest-leverage PM roles in growth. You'll work with a team of data scientists, machine learning engineers, and data engineers running Flo's production pLTV models across short-horizon (intra-day) and long-horizon (M15+) predictions. You'll drive accuracy improvements, expand signal coverage across platforms, and extend pLTV's reach into new decision domains. You'll also help scale Flo's in-house agentic experimentation system — already delivering 30%+ quality gains — and contribute to the next generation of Flo's marketing measurement stack, including Marketing Mix Modeling and incrementality testing. This is a senior IC role with company-wide visibility, partnering with leadership across User Acquisition, Finance, Analytics, and Engineering. It's equally hands-on in delivery: co-leading the team day-to-day with your engineering manager pair, writing the specs, defining the epics, staying close to the work. Your Experience Must have: * Proven experience owning machine-learning or data-driven products in production — predictive scoring, propensity, ranking, forecasting, or similar data-rich products. Strong fit for current Product Managers; also open to Engineering Managers, ML Engineers, or tech leads who have shaped product direction end-to-end and are ready to make the switch into a PM seat. * Hands-on delivery instincts — equally comfortable in Jira (writing specs, defining epics, refining the sprint backlog, unblocking the team) as in strategic planning and stakeholder management. Co-leads the team day-to-day with your engineering manager pair. * Hands-on partnership with data science and machine-learning engineering teams — partnering on model evaluation, retraining cadence, feature decisions, and release discipline. * Strong analytical fluency — SQL proficiency, comfort interpreting model evaluation metrics, and the habit of interrogating performance at segment, cohort, and campaign level rather than blended aggregates. * Demonstrated ability to influence senior cross-functional stakeholders across marketing, finance, analytics, and engineering — translating technical model behaviour into commercial decisions. * Comfortable in fast-paced, ambiguous environments — balancing platform investments against fast-cycle experimentation, with shifting priorities and competing demands. Nice to have: * Working knowledge of mobile and web user acquisition — how bidding, attribution, and campaign optimisation actually work, including privacy frameworks such as SKAN/ATT or Privacy Sandbox. * Hands-on experience with mobile attribution platforms (AppsFlyer, Adjust, Branch, Firebase) and modern measurement frameworks (SKAdNetwork, GA4). * Exposure to Marketing Mix Modeling, incrementality testing, holdout design, or causal inference techniques. * Familiarity with feature stores (Databricks, Tecton, Feast) and modern MLOps tooling. * Subscription-app, health & wellness, or femtech domain background. * Exposure to agentic AI or LLM-orchestrated workflows for ML experimentation, research, or model evaluation. What you'll be doing You'll be responsible for: * Owning Flo's pLTV product roadmap end-to-end across iOS, Android, and Web — driving accuracy improvements, expanding feature coverage, extending prediction horizons, and pushing pLTV into new decision domains (creative testing, product roadmap, pricing, hypothesis validation) alongside its existing UA and Finance use cases. * Partnering with data scientists and engineers on feature strategy — deciding which inputs the model consumes and ensuring those features are available reliably in production. * Operating rigorous release discipline — gated rollouts, shadow-mode evaluation, drift detection, automated retraining, and post-launch calibration — so production models stay accurate as data distributions and platform policies evolve. * Working closely with data scientists and analysts to investigate model quality issues — country-level miscalibration, cohort drift, signal anomalies — and feeding findings back into the next iteration. * Helping scale Flo's agentic ML experimentation system from hundreds toward thousands of model runs — compounding quality gains back into production. * Acting as the primary product partner to User Acquisition leadership — translating model behaviour into bidding decisions, framing trade-offs, and aligning on attribution-window strategy. * Reporting model performance and strategic recommendations into monthly leadership reviews and quarterly investment decisions. * Contributing to Flo's next-generation measurement stack — including Marketing Mix Modeling, incrementality testing, and causal lift methodology — so marketing investment decisions are grounded in causal, not correlational, signal. #LI-Hybrid #LI-AJ1 Annual Salary Range (ranges may vary based on skills and experience) £92,000—£115,000 GBP How we work 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 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 get We support impact with meaningful reward. Here’s what that looks like: * Competitive salary and annual reviews * Opportunity to participate in Flo’s performance incentive scheme * Paid holiday, sick leave, and female health leave * Enhanced parental leave and pay for maternity, paternity, same-sex and adoptive parents * Accelerated professional growth through world-changing work and learning support * In-person collaboration and work in a hybrid model, with 3 days per week spent in the office * 5-week fully paid sabbatical at 5-year Floversary * Flo Premium for friends & family, 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.

Join Proton and build a better internet where privacy is the default Proton was founded in 2014 by scientists from CERN on a simple truth: privacy is a fundamental human right. Since then, we’ve built the world’s largest encrypted email service (Proton Mail) and expanded into Proton VPN, Proton Drive, Proton Pass, and Proton Calendar—tools used by millions globally to protect their freedom, fight censorship, and keep their data safe. In some situations, Proton has literally helped save lives! We are profitable, independent (no VC control), and selectively hire from the top ~1% of applicants. Our 500+ team members across 50+ countries come from leading organizations and elite academic backgrounds. We move fast, keep hierarchy light, and prioritize impact over optics. If you want to do meaningful work with exceptionally high-caliber people, this is it. Join us and do work you can truly be proud of. Check our open-source projects here! The Proton Drive Desktop Team Proton Drive is our secure, private cloud storage and collaborative editing suite, with clients on Windows, Mac, iOS, Android, and Web. One platform is missing: Linux. You will build it from scratch. This is a greenfield project with high visibility inside Proton and across the open-source community — our entire client codebase is published under an open-source license, and this will be the first public example of how to build a native application on top of the Proton Drive SDK. You will work closely with our Windows and Mac engineers to ensure feature parity, and you will contribute to our platform-agnostic SDK and CLI tooling as the Linux surface area demands it. If building something that the Linux community has been waiting for, and doing it in the open, is the kind of work that gets you out of bed — this role is for you. Tech Stack and Tools * Linux desktop application development (GTK+ or Qt) * Rust (nice to have) * Git, CI/CD pipelines * Linux packaging and distribution (Debian, Fedora-based) What You'll Do * Own the design and implementation of the Proton Drive Linux desktop client, built greenfield from the ground up. * Ensure the codebase meets the standard expected of production open-source software — it will be read and built upon by developers beyond Proton. * Integrate deeply with Linux-specific system components, including the filesystem layer for our file synchronization engine. * Contribute to our platform-agnostic SDK and CLI tooling to ensure Linux features are properly exposed for scripting and cross-client use. * Build and maintain cross-client automated and end-to-end tests in collaboration with Windows and Mac engineers. * Define and implement application telemetry to support performance analysis, debugging, and customer support. * Own the build pipelines, packaging, and distribution across major Linux distros. Job requirements: * 5+ years of experience in software development of Linux-based desktop client software, both with and without a visible interface (i.e., GUI apps as well as CLI apps). * Applied best practices in code quality paradigms * Experience with DevOps principles and practices (CI/CD, etc) * Experience with source control flow through Git (code reviews, branching and merging, etc) * Open-source Linux development, distribution, packaging and maintenance for multiple distros (e.g. on Debian or Fedora-based platforms) * Overall, handling the entire SDLC, end to end Nice to have: * Experience in Linux desktop client development (in particular through the GTK+ framework, or alternatively QT) * Experience in Rust What we offer * Work that Matters: millions of people trust Proton with their privacy. We answer only to our users — not advertisers, not investors with conflicting agendas, not governments. The work you do here is real, and the impact is measurable. (read more about our impact here) * A great Team: Our team is diverse, collaborative, and tight-knit with people coming from all walks of life, including many of the world’s top academic institutions and organizations, such as MIT, Harvard, Stanford, Caltech, Cambridge, and ETH. * Technology: you'll get the right hardware and the right software you need to do your best work. * Learning & Development: we invest in your growth because sharp people make us better. Proton is one of the fastest ways to accelerate your career because you'll be thrown into real challenges, with real ownership, from day one. * Employee Benefits: your wellbeing isn't an afterthought. We offer strong health coverage, solid retirement options, generous leave, and wellness support so you can bring your best self to work every day * Stock Options: at Proton, we all have the opportunity to be owners of the company. From day one, you have a real stake in what we're building. When Proton wins, you win. * In-Person Collaboration: Amazing things happen when passionate, smart, and purposeful people get together in the same room. With offices across Geneva, Zürich, Barcelona, London and more, you'll spend most of your time collaborating face-to-face with people who genuinely care about what they're building * Food: Lunch and snacks are on us every day in our offices so you can focus on the work and not on what's for lunch. * Transport: getting to the office shouldn't cost you. We cover public transport, bike allowances, or parking, whichever works for you. * Flexible Working: you own your schedule. Set hours that work for you and your team — because outcomes matter more than when the clock says you started. Our commitment to diversity and inclusion At Proton, we believe diversity drives innovation and strengthens our mission to provide privacy as a default for all. We are committed to fostering an inclusive environment where all individuals, regardless of race, ethnicity, gender, age, sexual orientation, physical ability or socio-economic background feel valued and empowered. We strive to create equal opportunities, promote open dialogue and support continuous learning to ensure every voice is heard and respected. If you need any extra support or reasonable adjustments during the hiring process, please let your talent partner know. Candidate privacy notice When you apply for a position, refer a candidate or are considered for a role at Proton Technologies AG (Proton, we, us or our), your information is stored in Greenhouse, in accordance with its Service Privacy Policy. This information is used to evaluate your suitability for the posted position. We also retain this information for consideration for future roles that you may apply for or that we believe may align with your background and skills. If we no longer have a legitimate business need to process your information, we will either delete or anonymise it. Should you have any inquiries about how we use or manage your information or if you wish to access, correct or delete your data, please contact our privacy team at careers@proton.ch. Proton does not accept unsolicited CVs from any sources other than directly from candidates. We will not pay a fee for any placement resulting from an unsolicited offer, even if the candidate is subsequently hired by Proton. To learn more about our privacy policy, please visit our privacy policy page.   #LI-ONSITE