Sr. Full Stack Engineer

Get to Know Us

Horizon3.ai 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.

What You’ll Do

You’ll join a fast-paced, collaborative team of talented software engineers helping shape the future of autonomous security testing. While this is a full stack role, we’re specifically looking for engineers with strong backend experience who are comfortable building out front-end features when needed—not because it’s “beneath them,” but because they understand the value of end-to-end product delivery.

• Work across the stack to deliver scalable, secure, and high-performing features for our enterprise SaaS platform, with a primary focus on backend development using Python and GraphQL.

• Build and support front-end features in React/TypeScript as needed to complete user-facing workflows.

• Collaborate with Engineering, Product, and Design teams to break down features, own technical requirements, and help shape the roadmap.

• Contribute to architecture decisions, own key services, and guide system design as the platform evolves.

• Write high-quality code, enforce best practices through code reviews, and maintain strong test coverage.

• Ensure CI/CD reliability, infrastructure stability, and app performance in AWS.

• Lead by example, mentoring junior engineers and promoting a culture of technical excellence and continuous learning.

• Balance hands-on development with technical leadership responsibilities

What You’ll Bring 

• BS in Computer Science, Engineering, or equivalent technical background.

• 7+ years of experience building production applications, primarily focused on backend development.

• Strong prioritization skills to balance competing demands on team resources

• Proven experience delivering backend APIs (especially GraphQL) and working with modern web stacks.

• Comfortable contributing to and occasionally leading frontend development efforts in React/TypeScript.

• Experience troubleshooting production infrastructure (preferably in AWS).

• Experience collaborating with designers, developers, architects, and product managers.

• Experience working with AI-assisted development tools and interest in leveraging AI for productivity.

• Strong problem-solving skills, ownership mentality, and the ability to operate in a fast-paced environment with shifting priorities.

• Startup or high-growth environment experience: building features from idea to production with urgency and pragmatism.

Required Tech Stack Experience 

Must have a strong background building products and features with the following tech stack:

• ​​Python (strong backend proficiency expected)

• Javascript, React, Typescript

• GraphQL

• HTML/CSS/Flexbox

• Git

Preferred experience

• React Query

• WebSockets

• PostgreSQL

• Vite

• AWS

• GitLab CI/CD

• Familiarity with LLM integrations or prompt engineering

• Experience in Cyber Security (Defensive/Offensive)

Travel Required 

We are a fully remote company, and this job may require up to 15% of travel to be successful.

Perks of Horizon3.ai

• 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