--- title: 'Staff Software Engineer, Firewall at Horizon3 AI' canonical: 'https://feeny.ai/job/staff-software-engineer-firewall-horizon3-ai-united-states-xqqhv8nxev5h' type: 'job' last_seen: '2026-10-31' --- # Staff Software Engineer, Firewall at Horizon3 AI - **Company:** [Horizon3 AI](https://feeny.ai/companies/horizon3-ai) - **Location:** United States - **Employment:** full-time - **Work type:** remote - **Posted:** 2026-10-30 - **Last confirmed live:** 2026-10-31 - **Apply:** https://jobs.ashbyhq.com/horizon3ai/90a870d7-2a66-4245-9bfd-3f4d37d68882 ## Job description Get to Know Us 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 NodeZeroTM 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 IT Ops/SecOps teams, consulting pentesters, and MSSPs and MSPs. We are a fusion of former U.S. Special Operations cyber operators, startup engineers & operators, and formerly frustrated cybersecurity practitioners. We're committed to helping solve our common security problems: ineffective security tools and false positives, resulting in alert fatigue, blind spots, "checkbox” security culture, 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. ## What You’ll Do We’re hiring a Staff Software Engineer to serve as the hands-on technical lead for the Firewall pod within Precision Defense. NodeZero helps customers understand where Web Application Firewall policies do—and do not—protect them along validated attack paths, then take informed action. You’ll build and evolve the services and integrations that connect NodeZero with WAF management platforms, assess coverage, and turn validated findings into accurate, safe remediation guidance. You’ll partner with Product, Engineering, AI research, and the Attack team to turn WAF workflows and attack-path evidence into useful, verifiable customer outcomes. This role is a fit for an engineer who can make an ambiguous problem executable, lead technical direction across a workstream, and stay close to the code and customer impact from design through operation and iteration. ## What You’ll Do - Own the technical approach for the Web Application Firewall workstream, from problem framing and design through sequencing, delivery, operation, and iteration. - Design and build reliable integrations with WAF management platforms and their APIs, accounting for differences in vendor policy models and behavior. - Define correctness checks so recommendations address the validated path while preserving legitimate traffic and service availability. - Build durable workflows for long-running or resumable operations, with appropriate handling for retries, idempotency, timeouts, and partial failure. - Where the product supports configuration changes, design safety controls such as tenant-scoped authorization, least privilege, precondition checks, auditability, and validation or recovery paths, including staged rollout and fast rollback for rules that can affect live application traffic. - Build observability that helps engineers and customers understand what the system assessed, what it recommends, and why. - Make regular production-code contributions while shaping architecture, leading design and code reviews, and raising the bar for quality, testing, security, and operational readiness. - Partner with Product and adjacent technical teams to clarify scope, sequence work, manage dependencies, and connect technical decisions to customer outcomes. - Mentor engineers, lead through influence rather than direct people management, and surface risks and tradeoffs early and clearly in writing. ## What You’ll Bring - Staff-level technical leadership: you can set direction for a workstream, make and explain tradeoffs, and bring other engineers along. - Strong hands-on software engineering skills, including a record of designing, shipping, and operating production backend systems. - Product-minded judgment: you can turn a broad goal into a shared problem definition, a practical technical roadmap, and a valuable first release without blocking future evolution. - A reliability and security mindset: you account for failure modes, correctness, authorization, auditability, and operational needs as part of the design—not as follow-up work. - The ability to work effectively across Product, Engineering, research, and customer-facing teams, including communicating complex technical decisions to different audiences. - A collaborative approach to technical leadership: you raise the bar through design, reviews, mentorship, and clear written decisions rather than relying on authority. Required Tech Stack Experience - Expert-level proficiency in large-scale Python software development. - 8+ years experience leading technical work at Staff, Lead, or comparable scope, including architecture, implementation, and cross-team influence. - Working knowledge of WAF platforms and policy models (i.e. AWS WAF, Cloudflare, F5, Imperva, FortiWeb, or ModSecurity/OWASP CRS), including rules, managed rule groups, and how vendor-specific behavior affects request inspection and blocking decisions. - Proficiency in other modern backend languages such as Go, or Rust, or a comparable language. - Experience designing service-oriented systems, APIs, or integrations, including how they behave under failure and partial completion. - Strong systems-design skills and the ability to make sound tradeoffs across correctness, reliability, security, and maintainability. - Ability to translate ambiguous product or customer problems into concrete technical plans and deliver outcomes with cross-functional partners. - Clear technical writing and communication skills. What Sets You Apart? - Experience in adjacent areas such as API security, bot management, rate limiting, or application security testing (DAST/pentesting), or exposure to network firewall platforms and segmentation. - Experience integrating with security or infrastructure platforms whose APIs and policy models vary by vendor. - Experience building security products or systems that assess control coverage, validate attack paths, or produce remediation guidance. - Experience designing safe automation for changes that can affect customer environments, including authorization, audit, validation, and recovery considerations. - Familiarity with cloud environments, containerization, and operating services at scale. - Experience working closely with Product, AI or applied research, or security practitioners to turn domain expertise into customer-facing software. Travel Required We are a fully remote company, and this job may require up to 10% of travel to be successful. ## Compensation and Values At Horizon3, we believe that our people are our greatest asset, and our compensation philosophy reflects this core value. We are committed to fostering an environment where all employees feel valued, respected, and rewarded for their contributions. Our compensation structure is designed to be fair, competitive, and transparent, ensuring that every team member is recognized and compensated equitably across roles, levels, and locations. In accordance with various State’s transparency regulations, we provide the following salary range information for this position: - Base salary range: $225,000 - $265,000 annually. The exact salary will be determined based on the selected candidate’s location, qualifications, experience, and relevant skills. - Additional compensation: All full-time roles are eligible for an equity package in the form of stock options. ## Perks of Horizon3 - Inclusive Team: We value diversity and promote an inclusive culture where everyone can thrive. - Growth Opportunities: Be part of a dynamic and growing team with numerous career development opportunities. - 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. - Competitive Compensation: We offer competitive salary, equity and benefits. Our benefits include health, vision & dental insurance for you and your family, a flexible vacation policy, and generous parental leave. You Belong Here Horizon3 is not just an equal opportunity employer - we are a community that values diversity, equity, and inclusion as fundamental principles of our culture and success. We are dedicated to fostering a workplace where everyone feels welcome and respected, regardless of race, color, religion, sex, national origin, age, disability, veteran status, sexual orientation, gender identity or expression, genetic information, marital status, hair length or any other legally protected status by law. Our commitment to diversity and inclusion means we strive to attract, develop, and retain a workforce that reflects the varied communities we serve. We believe that diverse perspectives drive innovation and strengthen our ability to create cutting-edge cybersecurity solutions. At Horizon3, every team member is valued and supported in an environment that encourages personal and professional growth. We welcome candidates from all backgrounds and experiences, and we encourage all qualified individuals to apply. Come be a part of Horizon3, where your unique contributions are recognized, and your potential is limitless. Other Duties Please note this job description is not designed to cover or contain a comprehensive listing of activities, duties or responsibilities that are required of the employee. Duties, responsibilities, and activities may change at any time with or without notice. Application Note In any materials you submit, you may redact or remove age-identifying information such as age, date of birth, or dates of school attendance or graduation. You will not be penalized for redacting or removing this information. ## About Horizon3 AI ## Company Overview - **One-liner**: Horizon3.ai provides an autonomous penetration testing platform (NodeZero) that safely hacks production environments to identify and fix exploitable attack paths using AI. - **Entity Type**: Private (Series D – latest funding round in 2026, led by Prosperity7 Ventures) - **Headquarters**: San Francisco, California, United States (447 Battery Street, San Francisco, CA 94111) - **Founded**: 2019 - **Founders**: Snehal Antani (Co-Founder & CEO); founded by a mix of US Special Operations, US National Security, and cybersecurity industry veterans ## Core Business - **Primary industry**: Cybersecurity (autonomous penetration testing, vulnerability management, continuous security validation) - **Target customers**: B2B – large enterprises, Fortune 100, government agencies (NSA, CISA), healthcare providers, financial services, manufacturing, education, public sector - **Mission**: “Turn the map around” – using the attacker’s perspective to help enterprises prioritize defensive efforts. The company aims to shift the advantage from attackers to defenders by fighting AI with AI. ## Products & Services - **[NodeZero®](https://horizon3.ai/)**: Autonomous penetration testing SaaS platform. Safely runs real attack techniques in production environments (no agents, no disruption). Discovers and chains exploitable vulnerabilities, misconfigurations, harvested credentials, and dangerous defaults across external, identity, on-prem, cloud, and Kubernetes attack surfaces. Also includes Active Directory password auditing and phishing impact testing. Continuously validates fixes and repeats autonomously. ## Market Standing - **Valuation**: Not publicly disclosed - **Key Metrics**: - Annual Revenue: **$35.5M** (per LinkedIn) - Total Funding: **$187M** (per LinkedIn) / **$181M** (per CB Insights – conflicting reports; both cited) - **225,000+** production-safe tests completed - **5,000+** customers - **Notable Investors/Partners**: - SignalFire (lead in Seed, Series A, Series B) - Craft Ventures (lead Series C) - Prosperity7 Ventures (lead Series D – 2026) - **Growth Signals**: - Ranked **#1 in Security** on the 2025 Inc. 5000 list - **#3 overall** on the 2025 Deloitte Technology Fast 500 - Fast Company’s **Most Innovative Companies** (2026) – #1 in Security - Named to the **Fortune Cyber 60** (2023 & 2025) - Two-time **Black Unicorn Award** winner - Headcount grew **115.5% YoY** to 341 employees (LinkedIn) - Active job postings up **168.2% YoY**; operates in 14 countries ## Competitive Advantages - **AI-driven autonomous testing** that learns from hundreds of thousands of tests and uses the right AI (ML, GenAI) for each problem – delivers evidence-based results with **zero hallucinations**. - **Production-safe** – zero downtime across all production tests, trusted by the world’s most sensitive high-security environments (NSA, CISA, Fortune 10, major healthcare). - **No agents required** – fully self-service SaaS, safe to run continuously. - **Real attack techniques** – not a scanner; shows actual attacker paths and impact. - **Rapid verification** – instantly confirms fixes and repeats the cycle, enabling a continuous validation loop. ## Strategic Focus - **Continuous validation** – driving a loop of test-fix-verify-repeat autonomously. - **Fighting AI with AI** – building NodeZero to operate at machine speed against AI-powered attacks. - **Global expansion** – already in 14 countries, with active hiring in EMEA, APAC, and the Americas. - **Scaling the team** – 59 active job postings (as of mid-2026), with emphasis on engineering, sales, and customer success roles. ## Why Work Here - **Culture**: Rated **5.0/5.0 on LinkedIn** (76 reviews) with perfect scores for Culture (5.0), Career (4.9), Compensation (4.7), and Work-Life (4.6). Described as a “kick-ass organization hell bent on disrupting an industry” with a team of “motivated learn-it-alls.” - **Work Policy**: Remote-friendly (most roles listed as remote, HQ in San Francisco, CA). Offers flexibility across time zones. - **Notable Perks** (from Built In and LinkedIn): - Comprehensive healthcare (medical, dental, vision, FSA) - Life insurance, disability insurance - 401(k) with company matching - Equity and employee stock purchase plan - Generous parental leave and family medical leave - Performance bonuses - Job training, conferences, and customized development tracks - Promotion policies and career growth support - **Engineering Culture**: Built by US Special Operations and National Security veterans. Emphasis on high autonomy, real-world impact, and cutting-edge AI/security work. “If you want to be part of a kick-ass organization hell bent on disrupting an industry and keeping attackers at bay, let’s talk.” ## Sources 1. [horizon3.ai – Homepage](https://horizon3.ai/) 2. [horizon3.ai – About/Team](https://horizon3.ai/about-us/) 3. [LinkedIn – Horizon3.ai Company Page](https://www.linkedin.com/company/horizon3ai) 4. [Built In – Horizon3.ai Careers & Perks](https://builtin.com/company/horizon3ai) 5. 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