Horizon3 uses real-world attacks to safely show what attackers can actually do in your environment—so you can fix and prove what matters. Backed by NEA.
About the role
We have deep offensive expertise on this team: people who know exactly how to find and exploit these vulnerabilities by hand. What we need is an engineer who can turn that expertise into autonomous agent capability , the reasoning, orchestration, tooling, and evaluation that lets an LLM-driven agent do this work reliably, at scale, and unattended.
What they're looking for
- 5+ years building production software, with strong Python
- Hands-on experience building LLM-powered applications or agents , tool use / function calling, structured outputs, multi-step orchestration, and the glue that makes it all hold together
- A track record of making LLMs reliable in production , you've wrestled nondeterminism, designed around model limitations, and shipped something that worked when it mattered
- Real experience with evaluation : you've built or owned the harness that tells you whether a model or agent change is an improvement, not just a vibe
- Strong instincts for prompt and context engineering , and the judgment to keep the model's job small and well-scoped
- Solid software fundamentals — testing, observability, and the discipline to keep a complex agent debuggable
More about this role
Horizon3 is a fast-growing, remote cybersecurity company dedicated to the mission of enabling organizations to proactively find, fix, and verify exploitable attack vectors before criminals exploit them. Our flagship product, the NodeZero™ platform, delivers production-safe autonomous pentests and other key assessment operations that scale across the largest internal, external, cloud, and hybrid cloud environments. NodeZero has been adopted by organizations of all sizes, from small educational institutions to government agencies and Global 100 enterprises. It is used by ITOps/SecOps teams, consulting pentesters, and MSSPs and MSPs.
We are a fusion of former U.S. Special Operations cyber operators, startup engineers, and formerly frustrated cybersecurity practitioners. We're committed to helping solve our common security problems: ineffective security tools, false positives resulting in alert fatigue, blind spots, "checkbox" security culture, the cybersecurity skills shortage, and the long lead time and expense of hiring outside consultants. Collectively, we are a team of learn-it-alls, committed to a culture of respect, collaboration, ownership, and results.
We're building an...
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