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Salary: USD 199,750 - 235,000 / annual
Horizon3.ai is a fast-growing remote cybersecurity company building NodeZero, an autonomous pentesting platform that helps organizations proactively identify and fix exploitable attack vectors. The platform scales across internal, external, cloud, and hybrid environments and is used by ITOps/SecOps teams, consulting pentesters, MSSPs, and MSPs ranging from educational institutions to Global 100 enterprises.
As a Senior Backend Engineer on the External Attack team, you will own and operate core backend services powering NodeZero's external pentesting capabilities. You'll be responsible for the full lifecycle—from architecture and development through deployment and production operations—of services including the core Python API, data processing and ETL pipelines, datalake infrastructure, graph-based APIs, and container orchestration on Kubernetes. You'll be accountable for performance, scalability, and uptime of multiple services and will be a key contributor to user-facing product launches and platform stability.
Key responsibilities include: designing and maintaining features in the core Python API with focus on performance and maintainability; building and operating workflow orchestration for large-scale, long-running workloads using tools like Prefect or Temporal, including scheduling, retries, idempotency, and failure recovery; building orchestration that scales reliably across many concurrent workflows with clear visibility into progress and failures; reading, optimizing, and safely refactoring complex SQL in production; building and operating high-throughput data processing and ETL pipelines that transform raw assessment data into reliable, queryable datasets; contributing to datalake architecture on AWS including storage layout, partitioning, schema evolution, and query performance; deploying and managing services on Kubernetes with cluster operations, release management, and capacity planning; developing and extending GraphQL and graph-based APIs for exploring complex data relationships; owning observability, uptime, and scalability of services including metrics, tracing, alerting, and on-call participation; partnering with frontend engineers, product managers, and designers to translate backend capabilities into clear, responsive user experiences; contributing to systems architecture decisions and writing design documentation; and collaborating on data presentation to enhance user experience.
You should bring the ability to own and manage concurrent initiatives with sound prioritization and time management; a self-driven approach to conceiving and implementing solutions independently and collaboratively; a reliability mindset for distributed systems with design patterns for retries, partial failure, and recovery; strong desire to learn new technologies in a fast-paced Agile environment; excellent analytical and problem-solving skills with clear communication and attention to detail; a bias toward operational ownership and understanding how code behaves in production; strong technical writing for design docs, runbooks, and API documentation; and effective collaboration with designers, developers, and product managers.
The company is a fusion of former U.S. Special Operations cyber operators, startup engineers, and cybersecurity practitioners committed to solving common security problems: ineffective tools, alert fatigue, blind spots, checkbox security culture, skills shortage, and expensive consultant lead times. The culture emphasizes respect, collaboration, ownership, and results.
Up to 5% travel may be required. This is a fully remote role, though the company has a Chicago office where some roles require regular in-office presence.
REQUIREMENTS:
- Bachelor's Degree in Computer Science, Computer Engineering, or related field
- 7+ years professional software engineering experience using modern object-oriented or functional languages (Python, Java, Go, Scala, C++, TypeScript, etc.)
- Experience building and running workflow orchestration or distributed task-processing systems in production (e.g., Prefect, Temporal, Airflow, Celery, or similar)
- Hands-on experience designing and building high-throughput data processing systems and ETL pipelines
- Experience building applications on cloud computing platforms (AWS, Azure, GCP) using container technologies (Docker, Kubernetes)
- US citizenship or eligibility for US Federal Security Clearance (required due to customer/vendor security clearance requirements)
DESIRABLE QUALIFICATIONS:
- Deep Kubernetes experience including managing deployments, clusters, and troubleshooting production workloads
- Experience with durable-execution or workflow engines (Temporal, Prefect) including designing resilient, observable, and evolvable workflows
- Experience building GraphQL backends and working with graph databases
- Track record of owning observability, uptime, and scalability for production systems (Datadog, Prometheus, OpenTelemetry)
- Systems engineering and architecture experience with datalakes and cloud services
- Experience building platform capabilities or internal tooling that other engineering teams rely on
- Experience in cybersecurity or with attack surface and vulnerability data
