R+D Engineer

Barcelona; Geneva; 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 team: ProtonVPN runs on a distributed architecture of Linux servers and a set of apps available on each major platform (Windows, Android, iOS, macOS, and Linux) that interact with our infrastructure. As a member of the ProtonVPN Research and Development team, you will work on maintaining the security of ProtonVPN’s infrastructure, improving its overall performance, designing and implementing new features. On any given day, you might code in C or Rust, script in Python or Lua, create patches for the Linux kernel, or debug system-level issues on different operating systems. You will work in close collaboration with the entire ProtonVPN development team on any outstanding projects. You will face unique and varied challenges that will require continuouslearning. What you will do:

Being an active member of the ProtonVPN R&D team
Collaborating with app developers to help solve the various complex challenges related to (but not limited to) the networking stack of Linux, macOS, iOS, Android, and Windows systems
Helping develop innovative solutions to improve the connectivity, stability, performance, scalability, security, and resilience of ProtonVPN’sinfrastructureand client software, and extend their functionality
Contributing to existing open-source projects or creating new ones

What we are looking for:

Expert-level knowledge of operating system internals
Expertise with network protocols and implementation
A documented track record of contributions to system-level projects and applications
Experience with software development
Understanding of the principles of quality assurance

Bonus points for:

Expertise in Windows, macOS, or Linux system development
Extensive experience working with Linux kernel, Windows drivers, or macOS system extensions development
Strong understanding of system programming languages (C/C++, Rust, Go, Python, etc.)
Experience with debugging code and code profiling
Good understanding of TCP/IP protocol and settings (e.g., congestion algorithms)
Strong understanding of VPN protocols (particularly OpenVPN and WireGuard)
Experience with cryptography concepts (e.g., TLS certificates and public key infrastructure)

What We Offer:

Work that Matters: millions of people trust Proton with their privacy. We answer only to our users 6 not advertisers, not investors with conflicting agendas 6 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,...