Horizon3.ai · 9 hours ago
Agentic Offensive AI Engineer
Indianapolis, IN
Full-time
Hybrid
New Grad, Entry LevelHorizon3.ai is a fast-growing, remote cybersecurity company dedicated to enabling organizations to proactively find and fix exploitable attack vectors. They are seeking a junior engineer with a strong AI/ML foundation to develop AI systems for vulnerability detection and autonomous security testing, contributing to the design, training, and testing of intelligent agents that emulate real adversaries.
Artificial Intelligence (AI)Cyber SecurityEnterprise SoftwareMachine LearningNetwork Security
No H1B
U.S. Citizen Only
Responsibilities
Develop AI systems for vulnerability detection and autonomous security testing
Design and train reinforcement-learning and fine-tuning workflows (e.g., PPO, LoRA/QLoRA) to improve automated security agents
Automate security testing pipelines with Python and modern ML frameworks
Contribute to feature development from concept through deployment, including model evaluation and experiment tracking
Identify and document vulnerabilities in AI-native applications and LLM workflows
Research emerging AI security threats, prompt-injection tactics, and adversarial ML
Document findings and help build a technical knowledge base
Qualification
Required
Bachelor's degree in Computer Science, Machine Learning, Artificial Intelligence, Data Science, Software Engineering, Mathematics, Statistics, or a related field
Strong Python skills and comfort with data-science libraries (NumPy, pandas, scikit-learn)
Foundational knowledge of AI/ML concepts and frameworks (PyTorch, TensorFlow, or JAX)
Exposure to reinforcement learning or similar methods (deep Q-learning, PPO) through coursework, labs, or projects
Understanding of model training life cycle: data prep, feature engineering, and evaluation
Experience with Linux environments and Git version control
Interest in cybersecurity and ethical hacking
Strong problem-solving and clear communication skills
Must be located in or willing to relocate to the Indianapolis metropolitan area
US Citizen or GreenCard Holder
Preferred
Hands-on projects fine-tuning LLMs or training LoRA/QLoRA adapters
Experience with vector databases or retrieval-augmented generation (RAG)
Familiarity with AI security topics (model inversion, adversarial attacks)
Internship or academic work in reinforcement learning or autonomous agents
Contributions to open-source RL or adversarial-ML projects
Experience with Docker and containerized ML ops (Docker/Kubernetes)
Experience with cloud platforms (AWS, Azure, or GCP)
Security certifications (Security+, etc.) or active pursuit of them
Participation in CTF platforms (Hack The Box, TryHackMe, etc.) or AI/ML competitions (Kaggle)
Benefits
Deep Mentorship: Work side-by-side with experienced engineers to master real-world AI security pipelines
Career Growth: Opportunity to become a core technical leader as our AI offensive security stack expands
Hybrid Flexibility: 2–3 days a week in our Indianapolis office with flexible remote options
Competitive Entry-Level Compensation: Full benefits including health, vision, and dental
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.
Remote Work: We are a 100% remote company. Enjoy the convenience and work-life balance that comes with remote work.
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.
Additional compensation: All full-time roles are eligible for an equity package in the form of stock options.
Company
Horizon3.ai
Horizon3.ai offers an autonomous penetration testing platform that helps organizations proactively find and fix security vulnerabilities.
Founded in 2019
201-500 employees
Funding
Current Stage
Late StageTotal Funding
$178.5MKey Investors
New Enterprise AssociatesCraft VenturesSignalFire
2025-05-22Series D· $100M
2023-08-08Series C· $40M
2021-10-29Series B· $30M
Leadership Team
Snehal Antani
Co-Founder & CEO
Holly Grey
Chief Financial Officer
Recent News
2025-12-16
2025-12-16
Company data provided by crunchbase