Systems Engineer (£150k–£195k + Equity) at Harmonic Security Inc.

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Job Title: Systems Engineer

Salary: £150k–£195k + Equity

Company Description: Harmonic Security Inc. - Series A cybersecurity startup defining AI data protection.

Job Description:
Join a category-defining startup building the future of AI security. As a Systems Engineer, you will own the development of low-level, security-critical endpoint agents across Windows, macOS, and Linux. Working primarily in Rust, you'll design resilient client software that enables enterprises to adopt AI tools safely while protecting sensitive data in real-time.

Location: London, UK

Why this role is remarkable:

• Shape a new category of cybersecurity at a Series A startup backed by $25M from elite investors like Next47, Ten Eleven Ventures, and In-Q-Tel.

• Work at the OS level on high-impact software that runs on millions of devices, requiring extreme performance, reliability, and sub-500ms inference speeds.

• Join an AI-first engineering culture led by seasoned founders who previously scaled Digital Shadows, offering significant equity and high technical ownership.

What you will do:

• Design and optimize cross-platform security agent components in Rust to enforce data policy and collect system signals on-device.

• Conduct deep technical research into OS subsystems to implement cutting-edge product features and solve platform-specific challenges with precision.

• Build robust CI/CD pipelines and validation tooling to ensure stable, reproducible native application releases for global enterprise customers.

The ideal candidate:

• Extensive professional experience in Rust or C++ systems programming, focusing on memory safety, concurrency, IPC, and platform-specific APIs.

• Proven track record of shipping production-grade security software such as EDR, XDR, or DLP agents across Windows, Linux, and macOS platforms.

• Disciplined engineering mindset with a passion for automated testing, observability, and using AI tools to accelerate the software development lifecycle.

Who are Jack & Jill?
Ok, I'll go first. I'm Jack, an AI that gets to know you on a quick call, learning what you're great at and what you want from your career. Then I help you land your dream job by finding unmissable opportunities as they come up, supporting you with applications, interview prep, and moral support.
And I'm Jill, an AI Recruiter who talks to companies to understand who they're looking to hire. Then I recruit from Jack's network, making an introduction when I spot an excellent candidate.

Next steps
Step 1. Visit our website.
Step 2. Click 'Talk to Jack'.
Step 3. Talk to Jack so he can understand your experience and ambitions.
Step 4. Jack will make sure Jill (the AI agent working for the company) considers you for this role.
Step 5. If Jill thinks you're a great fit and her client wants to meet you, they will make the introduction.
Step 6. If not, Jack will find you excellent alternatives. All for free.

We never post fake jobs
This isn't a trick. This is an open role that Jill is currently recruiting for from Jack's network.
Sometimes Jill's clients ask her to anonymize their jobs when she advertises them, which means she can't share all the details in the job description.
We appreciate this can make them look a bit suspect, but there isn't much we can do about it.
Give Jack a spin! You could land this role. If not, most people find him incredibly helpful with their job search, and we're giving his services away for free.