Principal Endpoint Agent Engineer in City of Westminster

As an endpoint engineer, you'll help build and evolve the low‑level, security‑critical client software that powers Harmonic's platform. Our software must be fast, resilient, and trustworthy across operating systems and real‑world conditions. You'll have the opportunity to shape foundational agent architecture, influence how we collect and process signals on‑device, and set the technical bar for correctness and safety as we define a new category of AI security.

Responsibilities

• Design, implement, and optimise endpoint security agent components in Rust, targeting desktop and/or server platforms (Windows, macOS, Linux).
• Build robust tests, validation tooling and deployment mechanisms for client‑facing releases that impact our customers in their everyday work.
• Conduct exploratory technical research to understand the art of the possible and how to best approach implementation of new product features.
• Investigate and resolve platform‑specific issues with precision and speed.
• Work closely with security engineers, backend engineers, and product stakeholders to shape technical requirements.
• Ship production Rust or C++ code that runs safely and efficiently across platforms.
• Ensure components are well tested, observable, and resilient to partial failures or bad input.
• Identify performance or architectural bottlenecks before they reach users.
• Actively reduce complexity in critical code paths without compromising clarity or functionality.
• Consistently deliver high‑quality changes on a tight feedback loop, including regression‑safe updates.

Qualifications

• Strong hands‑on coding experience with Rust (or C++ with a strong willingness to learn Rust) in production systems.
• Solid grasp of systems programming concepts: memory safety, lifetimes, threads, channels, error handling, IPC.
• Familiarity with platform APIs and subsystems on Linux, Windows, and macOS.
• Experience building CI‑tested, reproducible builds for native applications.
• Proficiency with common developer tooling: Git, code review, CI pipelines, structured logging, crash analytics.
• Networking skills and security fundamentals is a plus.
• Strong development background and a rigorous approach to testing and validation.
• Relish the prospect of writing code that will run on millions of devices and needs to be reliable and performant around the clock.
• Enjoy working close to the OS and care deeply about software performance, correctness, and safety.
• (Previous kernel or system‑level development experience is a great nice‑to‑have.)
• Can build and ship reliable systems fast, with a sharp eye for edge cases and long‑term maintainability.
• Learn quickly and independently, maintaining great attention to detail and high standards under pressure.
• Have made contributions to open‑source Rust (or C++) projects or RFCs.
• Believe that good tooling and documentation are essential parts of engineering, not afterthoughts.
• Thrive in fast‑paced startup environments where ambiguity is the norm.
• See AI as a fundamental tool to help you build smarter, faster, and better.
• Actively use AI tools (Claude Code, Cursor, or similar) to accelerate your work across the entire lifecycle‑from writing and debugging to researching and prototyping.
• Stay current on how AI is changing the systems engineering domain and have opinions about where it helps and where it doesn't.
• Refuse to default to the playbook you've been running for the last decade, choosing instead to automate the mundane and rethink legacy workflows to focus on high‑expertise problems.

Benefits

• Competitive pay and meaningful equity with a direct stake in Harmonic's success.
• Comprehensive benefits, pension plan, generous PTO, and flexible hybrid work.
• A small, passionate team that values transparency, creativity, and learning.
• Thoughtful leadership that cares deeply about growth, impact, and people.
• Annual global offsites (past trips include Lisbon and Nashville).
• The chance to directly shape both our product and our culture as we build a category‑defining company.