Staff Backend Engineer, Internal

Get to Know Us

Horizon3.ai 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

As a Staff Backend Engineer on the Internal Attack team, you'll set technical direction for the backend systems that power NodeZero's internal pentesting capabilities, from architecture and development through deployment and production operations. You'll lead high-impact work across the services and data pathways that turn the attack team's knowledge-graph output into reliable customer-facing results, including the ETL pipelines, relational data model, SQL queries, GraphQL endpoints, and supporting APIs. You'll be a hands-on technical leader for this domain—resolving its hardest design and production problems, aligning partner teams, and raising the quality and reliability bar beyond your immediate team.

Responsibilities

Set the architecture and technical direction for core Python services and APIs, designing for correctness, performance, maintainability, and long-term evolution.

Lead complex backend initiatives from problem definition and design through delivery and production operation, coordinating dependencies across attack, frontend, data, and other engineering teams.

Design and evolve reliable processing workflows for large-scale, long-running internal assessments and data workloads, including scheduling, retries, idempotency, state management, and failure recovery.

Shape processing and data-access patterns to scale across concurrent workloads, with clear visibility into progress, failures, and throughput.

Lead the design and operation of high-throughput ETL pipelines that transform attack-team knowledge-graph output into reliable, queryable relational datasets for the customer portal.

Guide the attack-path data model and presentation layer so identity, privilege-escalation, and lateral-movement paths are represented accurately and consistently in customer results.

Bring strong judgment to complex SQL: you'll read and optimize raw SQL regularly here, not just ORM calls, untangling unfamiliar queries, identifying performance and correctness risks, and guiding safe production optimization or refactoring that others follow.

Define and evolve GraphQL and graph-based API patterns that let product components and customers explore complex relationships in internal attack data.

Own the operational health of the backend systems in your domain; establish and promote effective practices for observability, uptime, scalability, release readiness, and on-call response.

Drive system architecture decisions across team boundaries, make tradeoffs explicit, and write design documents that give teams a shared direction and reusable technical reference.

Serve as a technical leader in cross-functional planning, aligning backend investments with product priorities and communicating risks, dependencies, and options to technical and non-technical stakeholders.

Mentor and unblock engineers through design discussions, code reviews, and technical guidance; raise engineering standards and help others take on broader ownership.

Partner with frontend engineers, product managers, and designers to turn backend capabilities into a clear, responsive user experience, and ensure attack paths and assessment data are presented clearly.

What You’ll Bring

The ability to own multiple complex initiatives, make sound prioritization decisions, and keep work moving across teams with competing dependencies.

A self-driven, hands-on approach: you can set direction, make progress through ambiguity, and deliver independently while bringing others along, and you say plainly what is and isn't yet guaranteed.

A reliability mindset for distributed work: you design for retries, partial failure, and recovery, and methodically diagnose asynchronous systems and production issues.

Strong technical judgment: you weigh performance, correctness, scalability, operability, and maintainability, and clearly explain tradeoffs and their customer or business impact.

A track record of influencing technical decisions beyond your immediate team and building alignment across engineering and product partners.

A commitment to developing other engineers through mentorship, thoughtful reviews, and clear technical guidance.

Excellent analytical and problem-solving skills, clear communication, and attention to detail.

Strong technical writing for architecture proposals, design docs, runbooks, and API documentation.

A strong desire to keep learning new technologies in a fast-paced Agile environment.

Required Education / Experience

Bachelor's Degree in Computer Science, Computer Engineering, or a related field.

8+ years of professional software engineering experience using modern object-oriented or functional languages (Python, Java, Go, Scala, C++, TypeScript, etc.).

Demonstrated technical leadership on high-complexity backend or data-platform initiatives, including setting direction and delivering work across multiple teams or stakeholders.

Experience designing, building, and operating production data-processing, ETL, or distributed task-processing systems at scale.

Hands-on experience with backend APIs, relational data models, and SQL in production systems.

Experience building applications on cloud computing platforms such as AWS, Azure, or GCP, and using container technologies such as Docker.

What Sets You Apart

Deep experience shaping cross-team backend architecture and establishing practices that improve the quality, reliability, or operability of systems beyond your own team.

You can sit down with a slow query, explain-analyze it, and come back with a rewrite that changes the runtime by an order of magnitude, and you've set that bar enough times that it's routine on this team, not heroic.

You've built ETL that ran unattended against messy, real-world source data and didn't silently drop records or stall without alerting, and you've held it up under wildly uneven per-tenant scale.

You're comfortable being the connective tissue between backend, frontend, and data pipelines, and you set the patterns for the seam where they meet.

Fluency with the modern Python toolchain this team runs on, including SQLAlchemy, versioned migrations, uv, ruff, mypy, and pytest, and the inclination to raise those standards rather than just meet them.

Experience designing durable, observable data workflows with orchestration engines such as Temporal, Prefect, Airflow, Celery, or similar.

Deep experience with GraphQL backends and with graph databases such as Neo4j.

A track record of owning observability for what you ship, metrics, alerting, and dashboards (for example Datadog, Prometheus, or OpenTelemetry), so the team watches it in production, not you personally, and you raise that operational bar for others.

Systems engineer