Senior Performance Engineer

• Design and own Proton VPN’s performance framework, defining metrics and KPIs that reflect the real-world experience of users (time-to-connect, throughput, latency, stability, reconnection rates, etc.).
• Develop distributed testing systems that simulate real network conditions, including low bandwidth, packet loss, and high-latency scenarios.
• Continuously measure and analyze performance across platforms (desktop, mobile, backend) and regions to identify bottlenecks and regressions.
• Collaborate with backend, R&D, and client teams to optimize protocol handling, connection setup, routing, and encryption performance.
• Create dashboards, reports, and automated alerts to track global performance health.
• Contribute to the design of resilient connectivity strategies that adapt dynamically to variable network conditions.
• Serve as the performance champion within the engineering organization, mentoring others and driving a data-driven performance culture.

Technical Skills:

• 5+ years of experience in performance engineering or systems QA, ideally in networking, VPNs, or distributed systems.
• Knowledge of network protocols (TCP/IP, UDP, TLS, WireGuard) and performance profiling tools.
• Proven ability to analyze latency, throughput, and stability metrics across multiple layers (client, OS, transport, application).
• Proficiency in Python (or similar scripting language) for scripting and/or Rust/C/C++ for bench-marking, or systems analysis.
• Familiarity with network emulation and simulation tools (e.g., tc/netem, iperf, IPTables/nfTables…).
• Experience with monitoring and observability stacks (Grafana, Prometheus, Loki) and CI/CD pipelines.
• Cross-platform experience with Linux, macOS, Windows, Android, and iOS preferred.

Soft Skills:

• Analytical and methodical, yet creative in solving complex performance problems.
• Comfortable working with uncertainty and non-deterministic conditions.
• Collaborative mindset, able to work across client, infrastructure, and data teams.
• Strong communication and documentation skills in English.

• Office First: Collaboration is easier and more effective in person, which is why the company has  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 3 core days in the office.
• Technology: Company provides 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 their offices.
• Transport: Company will always support our employees with transport costs through subsidizing public transport, bike allowances, or parking spaces based on your office location.
• Stock Options: At Proton, all employees are 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: Company is 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 they  put our users and community first in everything they do.