Senior .NET Developer (Desktop/SDK)

About the role

Proton is looking for a Senior .NET Developer to design, build, maintain and evolve the sync SDK that powers Proton Drive's desktop applications across Windows, macOS and Linux. You will work on core internals, cryptographic operations, and ensure resilient, privacy‑by‑default experiences for millions of users.

Key responsibilities

• Develop and enhance the sync SDK and shared desktop application components.
• Implement file system interactions, state synchronization, and cryptographic workflows.
• Collaborate with backend engineers to integrate new features and API changes.
• Invest in test automation, monitoring, and alerting to maintain high reliability.
• Participate in deployment, incident response, and gradual roll‑out processes.

Required profile

• Strong experience in .NET development.
• Proven expertise with concurrent multi‑threaded programming.
• Optional experience building and maintaining desktop applications.
• Working knowledge of file systems and Git.
• Bachelor's or master’s degree in a relevant field and experience owning large software components.

Required skills

• .NET
• Multi‑threaded programming
• Desktop application development
• File system knowledge
• Git

What we offer

• Office‑first environment with flexible remote work up to 30% of the time.
• All necessary devices, software, lunch and snacks at office locations.
• Transport subsidies, bike allowances or parking based on office.
• Stock options and ownership in the company.
• Flexible working hours, learning and development programs, and comprehensive health and retirement benefits.