Principal Endpoint Agent Engineer

Harmonic Security lets teams adopt AI tools safely by protecting sensitive data in real time with minimal effort. It gives enterprises full control and stops leaks so that their teams can innovate confidently.

We are led by cybersecurity experts and backed by top investors including N47, Ten Eleven Ventures, and In-Q-Tel.

As AI adoption accelerates inside the enterprise, Harmonic’s ability to safely observe, control, and enforce policy at the endpoint is mission‑critical.

This role sits at the core of that challenge. 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.

Harmonic exists to help enterprises adopt AI safely and  hold ourselves to the same standard. Everyone at Harmonic actively uses AI tools to do their best work, from research and writing to building processes and automating workflows. We expect every new hire to bring curiosity about AI and a willingness to use it to work smarter, faster, and more creatively. For some roles, that means tinkering and staying open to new tools.

For others, it means building entirely new systems with AI at the core. We'll be clear about what we expect for each role, and we'll give you the tools and support to get there.

Our Product Delivery team is the engine that turns vision into impact. We ship early and often, getting valuable features into the hands of customers quickly and iterating from there. We work in the open by default, sharing progress and ideas, and we trust each other to own outcomes. We’re a small but mighty crew where every person plays a critical role and we’re committed to using AI to work smarter and faster.

We’re looking for a hands‑on software engineer with deep expertise in Rust (or C++ with a strong willingness to learn and embrace Rust as your primary language) to help us build and evolve security‑critical client software. You will work on low‑level security agents and cross‑platform components that run on user devices, with a strong emphasis on robustness, performance and security. Your work will power core functionality in how we collect signals, and manage on‑device controls for app usage and data movement.

You will join a fast‑moving team that ships frequently and cares about correctness, observability and maintainability.

• 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

• You’ve shipped production Rust or C++ code that runs safely and efficiently across platforms

• Your components are well tested, observable, and resilient to partial failures or bad input

• You identify performance or architectural bottlenecks before they reach users

• You actively reduce complexity in critical code paths without compromising clarity or functionality

• You consistently deliver high‑quality changes on a tight feedback loop, including regression‑safe updates

• 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…