Senior Software Engineer, Agentic Systems
Horizon3 AI3 months ago
Remote, United StatesSenior
Base Salary
$169k - $208k/yr
Responsibilities
- Build and evolve the agent harness and orchestration loop that enables an LLM to reason over applications, form attack hypotheses, act, and verify results.
- Design probing and exploitation tools, tool-shaped feedback, structured outputs, and validation layers for reliable agent behavior.
- Translate offensive-security expertise into repeatable autonomous agent capabilities in partnership with offensive engineers.
- Own evaluation infrastructure, including benchmark suites, failure-mode taxonomies, and regression detection across the attack pipeline.
- Manage production LLM inference, including model selection, prompt and context engineering, and cost and latency control on AWS Bedrock.
- Ensure production safety and eliminate false positives by making every reported finding real and reproducible.
Requirements
- 5+ years of production software development experience with strong Python skills.
- Hands-on experience building LLM-powered applications or agents, including tool use or function calling, structured outputs, and multi-step orchestration.
- Experience making LLM systems reliable in production by designing around nondeterminism and model limitations.
- Experience building or owning evaluation harnesses, benchmarks, and regression detection for models or agents.
- Strong prompt and context engineering judgment.
- Solid software fundamentals, including testing, observability, and maintainable debugging practices.
- Working knowledge of web application security, including broken access control, IDOR/BOLA, SQL injection, XSS, SSRF, and SSTI, is desirable.
- Experience with agent evaluation harnesses, synthetic environments, CVE-based targets, or capture-the-flag scoring is desirable.
- Experience with agent frameworks and graph data models such as Neo4j is desirable.
- Experience with agent fine-tuning or reinforcement learning methods such as SFT, GRPO, and reward design is desirable.
- Offensive-security experience through CTFs, bug bounty work, pentesting, or research is desirable.
Benefits
- Remote and hybrid work options depending on role and location, including a Chicago office with regular in-office presence for some roles.
- Health, vision, and dental insurance for employees and families.
- Flexible vacation policy.
- Generous parental leave.
- Equity package in the form of stock options for all full-time roles.
- Inclusive culture, career development opportunities, and collaborative work environment.
Tech Stack
Neo4jPython
Categories
About Horizon3 AI
Horizon3 AI builds NodeZero, a proactive security platform that autonomously performs penetration testing and validates attack paths across on‑prem, cloud, and hybrid environments. The company sells its software by subscription to security and IT teams at enterprises and government agencies, helping prioritize and verify fixes. Founded in 2019 and headquartered in San Francisco, it is privately held and serves customers across regulated industries and the public sector.