Senior iOS Software Engineer - London

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.

The Role

Based in our London office, you’ll join one of several high-impact product teams across Proton Mail, Proton Drive, and Proton Wallet/Payments and Proton Account, helping build privacy-first products used by millions around the world. Whether it’s secure communication, encrypted cloud storage, 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 experiences on Apple platforms, helping 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 iOS applications.
• You care deeply about product quality, usability, and delivering exceptional user experiences.
• 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, and mobile memory management.
• 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 communicating with the iOS application via generic interfaces.

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.
• 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.