Senior Performance Engineer

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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.

What you will do

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- 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 integral 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.

Job requirements
Technical Skills

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- 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.).
- Proven ability to analyze latency, throughput, and stability metrics across multiple layers (client, OS, transport, application).
- Proficiency in Python (or similar scripting language).
- 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

📌 Senior R&D Engineer (Barcelona)
🏢 proton tehnologies
📍 Barcelona