iOS Software Engineer (Inbox) in London

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 organisations and elite academic backgrounds. We move fast, keep hierarchy light, and prioritise 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

As an engineer on our iOS team you’ll build and ship features across Proton’s apps on iPhone, working closely with product and engineers across the company to define what “great” looks like on Apple platforms. Our codebase is primarily Swift with some Go, and we’re moving to a platform‑independent Rust logical core that communicates with Swift via a generic interface, so Rust experience is a strong plus but not essential. Quality is central to the role: you’ll contribute to and maintain our testing stack, including unit tests for business logic, stubbed API tests for pseudo‑integration, snapshot tests for UI and XCUITest for end‑to‑end user flows. You’ll join a team that pairs deep technical expertise with an obsession for simple, usable interfaces, shipping privacy‑preserving products used by millions.

What we are looking for:

• You have experience in iOS in particular with Swift.
• You have a passion for mentoring other engineers and helping them grow.
• You are passionate about user interaction, usability, and providing an excellent user experience.
• Demonstrated experience driving change within an organisation and leading complex technical projects.
• Extensive experience building maintainable and testable code bases, including API design and unit testing techniques.
• Extensive experience with concurrent programming and mobile memory management.
• A strong grasp of scalable software architecture and software engineering best practices.
• An intuition for optimal user experience and design.
• Rust experience not required, but a major plus.
• Deep understanding of APNs, UNUserNotificationCenter and iOS background execution (silent pushes, background app refresh, background URLSession), and how these impact app reliability.
• Experience building offline‑first data flows with local persistence (Core Data, SQLite, Realm or similar) and conflict‑free sync.

What We Offer:

• Office First: Collaboration is easier and more effective in person, which is why we have offices in Geneva, Zurich, Prague, Barcelona, Paris, London, Vilnius, Skopje, and Taipei. You can also enjoy working from home up to 30% of the time, while enjoying great company during our three core days in the office.
• Technology: We provide all the devices and software you need to excel in your role, ensuring you have the best tools at your disposal to achieve your goals.
• Food: Lunch and snacks are provided by Proton every day at our offices.
• Transport: We will always support our employees with transport costs through subsidising public transport, bike allowances, or parking spaces based on your office location.
• Stock Options: At Proton, we are all owners of the company and you get stock options when you join us.
• Flexible Working: You can define your own working hours as long as it works with team meetings.
• Learning and Development: We are committed to your professional growth. Proton offers various learning opportunities, including training programs, conferences and events, and continual learning.
• Employee Benefits: Comprehensive health insurance plans, competitive retirement savings options, generous vacation and leave policies, and wellness programs.

Work that Matters: Proton is a community‑first organization, started with the support of a crowdfunding campaign and built with community input. To this day, Proton’s only source of revenue is user subscriptions. Over 100 million people trust and support Proton, and we put our users and community first in everything we do.

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 their 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.