---
title: 'WebApp Offensive Security Software Engineer at Horizon3 AI'
canonical: 'https://feeny.ai/job/webapp-offensive-security-software-engineer-horizon3-ai-united-states-njm6wjvdmpmd'
type: 'job'
last_seen: '2026-10-31'
---

# WebApp Offensive Security Software Engineer at Horizon3 AI

- **Company:** [Horizon3 AI](https://feeny.ai/companies/horizon3-ai)
- **Location:** United States
- **Compensation:** $196k–$242k
- **Employment:** full-time
- **Work type:** remote
- **Posted:** 2026-10-30
- **Last confirmed live:** 2026-10-31
- **Apply:** https://jobs.ashbyhq.com/horizon3ai/169d3dde-b8e7-4545-a5a4-cd5cc882c101/application

**Skills:** Web Application Penetration Testing, SQL Injection, XSS, SSRF, SSTI/CSTI, IDOR/BOLA, Authentication Bypass, Path Traversal, LFI, Burp Suite, Browser Developer Tools, Python, Proof-of-Concept Exploit Development, Jira, Nuclei Templates, sqlmap, Custom Burp Extensions, Postgres, Neo4j, LangChain

> This role involves performing hands-on web application penetration tests to identify vulnerabilities and edge cases that automated tools miss. The engineer partners with software developers to translate findings into product improvements and maintains regression test libraries for the NodeZero platform.

## Job description

Get to Know Us Horizon3 is a fast-growing, remote cybersecurity company dedicated to the mission of enabling organizations to proactively find and 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 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, 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.

Summary We're looking for a Senior/Staff Offensive Security Software Engineer with extensive web application penetration testing experience and a growing interest in AI-enhanced security techniques. You will have a significant impact on how we deliver value to our customers by designing, developing, and integrating web application penetration testing content into the NodeZero platform. This position requires practical expertise in full-scope web application testing, proven software development skills, and enthusiasm for leveraging emerging AI technologies to advance offensive security capabilities.

Essential Functions

- Perform hands-on, full-scope web application penetration tests against real customer applications, alongside benchmark and lab targets, to surface vulnerabilities and attack paths.
- Review NodeZero results on live customer engagements to identify coverage gaps, blind spots, and missed opportunities — the edge cases and corner-case attack scenarios that autonomous testing doesn't yet handle.
- Manually reproduce and validate those edge cases, building reliable, production-safe proof-of-concept exploits and clear test cases that demonstrate the gap end to end — including against live customer environments without disrupting them.
- Partner closely with software engineers to translate your findings into product improvements — defining detection logic, attack content, expected behavior, and remediation so NodeZero handles those cases going forward.
- Build and maintain a library of regression and benchmark test cases so newly added coverage doesn't silently regress over time.
- Monitor production pentests for missed findings and false positives; create and triage Jira tickets to drive issues to resolution.
- Work directly with customers and internal teams to investigate findings, explain attack paths, and address questions about web application coverage and results.
- Author technical blog posts and research write-ups showcasing new exploits, edge cases, and attack methodologies.
- Mentor teammates and contribute to continuous improvement of team processes, methodology, and testing standards.

Competencies/Requirements

- Experience conducting full scope web application pentests
- Experience with proxy tools like Burp and with browser developer tools
- Proficient in object-oriented programming and test-driven development, with strong analytical and problem-solving skills.
- Experience applying AI-assisted development tools to security research and automation tasks
- Curiosity about emerging AI technologies.
- Skilled in designing, evaluating, and communicating technical solutions across systems, APIs, algorithms, and data structures.
- Familiarity with relational and graph databases, particularly Postgres and Neo4j.
- Strong written and verbal communication, including technical documentation.
- Ability to manage multiple priorities, work independently, and mentor teammates of varying experience levels.
- Quick to learn and adopt new technologies as needed.
- History of recognized security research, including documented CVE discoveries and responsible disclosure
- Track record of successful bug bounty contributions

Desired/Nice to Have

- Experience developing software and automation to aid in web application pentesting
- Background in large-scale software development projects.
- Experience fine-tuning language models or implementing retrieval-augmented generation (RAG) for security-focused applications.
- Experience with AI/LLM tools for building agentic workflows (e.g., LangChain, LangFlow) and integrating contextual data using protocols like Model Context Protocol (MCP).

Expectations:

- Outstanding problem-solving aptitude.
- Be self-motivated and highly energetic to have the ability to operate effectively with limited supervision and guidance.
- Work with our security researchers to understand the technical aspects of reverse engineered exploits and weaponizing these exploits into the product.
- Strong technical documentation and communication skills.
- Document findings, methodologies, and recommendations for both technical and non-technical stakeholders.
- Proficient in designing, presenting, and evaluating technical solutions.

What makes you stand out:

- Demonstrated examples of using AI to enhance or automate exploit development
- OSCP (Offensive Security Certified Professional) Certification.

## 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.

## 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: $196,000 - $242,000. 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.

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, 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.

## 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. [CB Insights – Horizon3.ai Profile](https://www.cbinsights.com/company/horizon-3-ai)

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