Senior Foundation Engineer (Drive)

Proton, the privacy‑first company founded by CERN scientists, builds encrypted services such as Proton Mail, VPN, Drive, Pass and Calendar for millions worldwide. The Senior Foundation Engineer for Drive will join the team that underpins Proton Drive, ensuring that the core libraries and SDKs work reliably across all client platforms. Each day the engineer will design and implement the central C#, TypeScript and Rust libraries that power Drive’s desktop, mobile and web experiences. They will guarantee cross‑platform performance, conduct thorough code reviews, and collaborate closely with backend, frontend, mobile and desktop developers to integrate these components smoothly. Maintaining documentation, supporting the RFC process and using observability tools like Grafana, Prometheus and Sentry are also part of the routine, as is running automated tests through GitLab CI and Playwright. The role requires strong expertise in C#, TypeScript and Rust, as well as practical experience building SDKs that span multiple environments. Candidates must be comfortable providing language bindings for Swift and Kotlin and be familiar with the monitoring and CI/CD stack mentioned above. A senior‑level background in designing reusable libraries and a track record of delivering high‑quality, performant code are essential. Experience with cryptographic performance work, knowledge of Swift or Kotlin, and an interest in shaping a growing platform are considered advantageous. Proton’s team is distributed across more than 50 countries, operates without venture‑capital pressure, and values impact over hierarchy, offering a fast‑moving environment where senior engineers can evolve into technical leadership or management roles.