Senior Performance Engineer; VPN

Overview

Join Proton and build a better internet where privacy is the default.

At Proton we believe that privacy is a fundamental human right and the cornerstone of democracy. Since our inception in 2014, founded by a team of scientists from CERN, we have dedicated ourselves to providing free and open‑source technology to millions worldwide, ensuring access to privacy, security and freedom online.

Our journey began with Proton Mail, the largest secure email service globally, and has since expanded to include Proton VPN, Proton Calendar, Proton Drive and Proton Pass. These tools empower individuals and organizations to take control of their personal data, break away from Big Tech’s invasive practices and defeat censorship. Our work impacts hundreds of millions of lives, from activists on the front lines defending freedom to leaders in governments protecting sensitive data;

some cases, Proton’s services have even been instrumental in saving lives by enabling secure and private communications in high‑risk situations.

Proton is a profitable company that does not rely upon VC funding, supporting over 100 million user accounts with a growing team of over 500 people from over 50 different countries. We value intelligence, learning, potential and ambition in our hiring process. Adaptability is key as we navigate uncharted territories and redefine how business is conducted online.

Hiring at Proton is highly selective, with less than 1% of candidates hired. We believe smaller teams of exceptional talent will always prevail over larger teams with lower talent density. You will have the opportunity to work with many of the world’s top minds in their fields, ranging from former international math and science olympiad winners to chess champions.

We have a global mindset and big ambitions but remain a start‑up  value empowerment and flexibility and keep our structure flat to keep moving fast and avoid unnecessary politics. Tired of blending into the crowd? Join us and do work you can truly be proud of.

Check our open‑source projects here!

Proton VPN enables millions of people to connect securely and privately even in places where the internet is restricted or unreliable. Delivering that experience means our service must perform flawlessly under highly variable real‑world conditions.

• 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.

• 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, Wire Guard) 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 benchmarking or systems analysis.
• Familiarity with network emulation and simulation tools (e.g. tc/netem, iperf, IPTables/nf Tables).
• Experience with monitoring and observability stacks (Grafana, Prometheus, Loki) and CI/CD pipelines.
• Cross‑platform experience with Linux, macOS, Windows, Android and iOS preferred.

• Analytical and methodical yet creative in solving complex performance problems.
• Comfortable working with…