# Senior Software Engineer, Agentic Systems at Horizon3.ai

- Company: Horizon3.ai
- What the company does: 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.
- Company website: https://horizon3.ai/
- Type: Startups (AI role)
- Level: Senior
- Location: US, Remote
- Work setup: Remote
- Pay: $169K to $208K base salary per year (USD)
- Posted: 2026-08-26
- Apply by: 2026-10-10
- Apply: https://jobs.ashbyhq.com/horizon3ai/e36e9f43-c831-43ac-85b3-782b28bef222
- Page: https://www.1752.vc/careers/jobs/horizon3-ai-senior-software-engineer-agentic-systems/

## 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

Tags: Engineering