Horizon3.ai logo
Horizon3.ai

Continuous, autonomous pentesting, powered by NodeZero. Are your systems secure? Don't wait for a breach to find out!

Senior Software Engineer

Full-stack EngineerSoftware EngineerFull TimeRemoteSeniorTeam 51-200Since 2019H1B No SponsorCompany SiteLinkedIn

Location

United States

Posted

1 day ago

Salary

$169K - $208K / year

Seniority

Senior

Professional Certificate5 yrs expEnglishAWSPython

Job Description

Senior Software Engineer

Horizon3.ai

• Build and evolve the agent harness and orchestration that turns an LLM into a reliable autonomous pentester, the loop that reasons over an application, forms attack hypotheses, acts, and verifies results. • Design the tools and tool-shaped feedback the agent uses to probe and exploit, and the structured-output and validation layers that keep it reliable (e.g., hook-enforced mandatory validation, schema-constrained outputs). • Translate the team's offensive expertise into repeatable agent capabilities — partnering directly with our attackers to encode how they think into something the agent can do consistently. • Own and grow our evaluation infrastructure: benchmark suites, a failure-mode taxonomy across the pipeline (discovery → hypothesis → exploitation → verification), and regression detection, so we actually know whether the agent is getting better. • Manage LLM inference in production: model selection, prompt and context engineering, and keeping cost and latency under control (we run on AWS Bedrock with centralized cost tracking). • Hold the line on production-safety and no-false-positives, every finding the agent reports has to be real and reproducible.

Job Requirements

  • 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.
  • Ownership mentality, comfortable owning a critical, fast-moving subsystem end to end.

Benefits

  • Health, vision & dental insurance for you and your family
  • Flexible vacation policy
  • Generous parental leave
  • Growth Opportunities: Be part of a dynamic and growing team with numerous career development opportunities.
  • Inclusive Team: We value diversity and promote an inclusive culture where everyone can thrive.
  • Innovative Culture: Work in a collaborative environment that encourages creativity and out-of-the-box thinking.
  • Hybrid & Remote Work: We embrace a mix of remote and hybrid work models depending on role and location, including our Chicago office, where some roles require regular in-office presence.

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