Senior Android Developer (Drive)

About Proton  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 Role Based in our London office, you’ll join one of several high-impact product teams across Proton Drive, Payments and Account, helping build privacy-first products used by millions around the world. Whether it’s encrypted cloud storage, secure account infrastructure, or the future of private financial tools, you’ll work on technically ambitious products with real-world impact. As a senior engineer, you’ll collaborate closely with product, design, and engineers across Proton to build and ship high-quality Android experiences using Kotlin, Jetpack Compose, and an increasingly shared Rust core. You’ll take end-to-end ownership of your work and help define what “great” looks like for privacy-focused consumer products at scale. What we are looking for * You have extensive experience building and shipping high-quality Android applications using Kotlin * You have strong experience with Jetpack Compose and modern Android development practices * You care deeply about product quality, usability, and delivering exceptional user experiences * You have experience taking end-to-end ownership of features, from scoping and technical design through to delivery and iteration * You have strong experience building maintainable, scalable, and testable mobile architectures * You are comfortable working across large codebases and collaborating across multiple teams * You have experience mentoring engineers and raising the technical bar within a team * You have a strong understanding of performance, concurrency, multithreading, and mobile memory management * You understand mobile scalability considerations, including caching, network usage, responsiveness, and offline behaviour * You are comfortable navigating ambiguity and contributing to product and technical discussions * Experience with privacy, security, encryption, sync systems, or offline-first architectures is a strong plus * Rust experience is a plus, but not required, as we continue moving towards a platform-independent Rust logical core that communicates with our Android applications through generic interfaces Even if you don’t meet all the requirements listed above but feel you could still be a great fit, please do apply. 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) * 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. * 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 * 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

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 an Android Engineer at Flo, you'll help shape the mobile experience for millions of people, and do genuinely meaningful work in women's health. Our app is trusted by 1 in 4 women aged 18–44 in the US and used across 100+ countries, with machine learning and AI powering accurate cycle predictions and personalised, medically credible health insights. We build large-scale mobile applications with rich, intuitive interfaces - optimised for speed, accessibility and privacy. You'll join a cross-functional team working across the full mobile lifecycle, from feature ideation through to release and iteration, with real ownership over value delivery end to end. We're not a feature factory. Our engineers are pragmatic problem-solvers who thrive in fast-moving environments and care about what they ship. You'll have genuine scope to experiment, lead ambitious product initiatives and implement solutions that matter - not just clear a backlog. Flo is a constantly evolving product, and we give our engineers the trust and autonomy to evolve it. Your Experience Must have: * 7+ years of hands-on Android development experience, with a track record of shipping and maintaining production applications at scale * Experience building large, complex mobile applications with polished, performant UIs - ideally for global consumer audiences * Strong proficiency in Java, with solid object-oriented design principles and a keen eye for clean, maintainable code * Deep knowledge of the Android ecosystem - including platform fragmentation, UI design patterns, and delivering consistent experiences across a wide range of screen sizes and devices * Solid familiarity with Google technologies, Play Store submission processes, and Google's development guidelines * A good grasp of the full mobile product lifecycle, with practical experience working within Agile teams Nice to have: * Knowledge of Kotlin programming language, Clean Architecture and reactive programming * An eye for UX and interaction design - you care about how things feel, not just how they work * Hands-on experience with mobile CI/CD tooling, including build, test and release automation * Experience integrating with analytics and BI systems, including A/B testing frameworks * Experience with alternative Android markets * Experience optimising data usage over mobile networks and building offline-first applications What you'll be doing You'll be responsible for: * Developing features using modern frameworks, libraries and in-house components - contributing to a shared codebase built to last * Delivering polished, intuitive user experiences that meet a high bar for design and usability * Maintaining and improving a continuous delivery pipeline, ensuring fast, reliable and safe releases to production #LI-Hybrid #LI-AJ1 Annual Salary Range (ranges may vary based on skills and experience) £95,000—£120,000 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.