Job Title
Principal Systems Engineer
Salary
£150k-£195k + Equity
Company Description
Harmonic Security Inc. is a ~$25M Series A cybersecurity startup backed by Next47 and Ten Eleven Ventures, defining the AI security category. They build zero-touch data protection platforms that allow enterprises to safely adopt AI tools by protecting sensitive data at the endpoint in real time with sub-500ms inference.
Job Description
As a Principal Systems Engineer at Harmonic Security Inc., you will lead the development of low-level, security-critical endpoint agent software. Operating across Windows, macOS, and Linux, you’ll build high-performance Rust components that monitor and protect data movement. This is a mission-critical role defining how enterprises secure their AI-driven future at the OS level.
Location
London, UK
Why this role is remarkable
- Build a category-defining product at a $25M Series A startup founded by seasoned cybersecurity leaders who previously built Digital Shadows.
- Work at the cutting edge of AI-first security, writing high-performance Rust code that runs on millions of devices with sub-500ms latency.
- High-impact leadership role reporting to the VP of Engineering, influencing the core architecture and technical direction of the entire endpoint platform.
What You Will Do
- Design and optimize security-critical endpoint agent components in Rust, ensuring reliability across Windows, macOS, and Linux platforms.
- Architect foundational agent systems for signal collection and on-device controls, setting the technical bar for correctness, performance, and safety.
- Work closely with backend and security engineers to bridge low-level system signals with enterprise-grade policy enforcement and real-time observability.
The ideal candidate
- Strong production experience in Rust or C++, with a deep understanding of memory safety, concurrency, and systems programming fundamentals.
- Proven track record building security-critical client software like EDR, XDR, or DLP agents across multiple operating systems.
- A proactive, AI-first mindset, comfortable using tools like Cursor or Claude to accelerate development and solve complex, low-level technical challenges.
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