Senior Performance Engineer
We are looking for a Senior Performance Engineer to lead our efforts in making Proton VPN the fastest, most resilient, and most reliable VPN service in the world.
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 general 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.
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, debugging, manipulating, and performance profiling tools.).
~ Proficiency in Python (or similar scripting language).
~ Familiarity with network emulation and simulation tools (e.g., Experience with monitoring and observability stacks (Grafana, Prometheus, Loki) and CI/CD pipelines.
~ Cross-platform experience with Linux, macOS, Windows, Android, and iOS preferred.

Experience with Rust/C/C++/System development.

Analytical and methodical, yet creative in solving complex performance problems.
Collaborative mindset, able to work across client, infrastructure, and data teams.
Strong communication and documentation skills in English.
Office First: You can also enjoy w

📌 Senior Technology Development Engineer (Barcelona)
🏢 proton tehnologies
📍 Barcelona