Senior Backend Engineer, External

Horizon3

22h•$199,750 - $235,000•Remote

About The Position

As a Senior Backend Engineer on Horizon3’s External Attack team, you will contribute to the backend services powering NodeZero’s external penetration testing capabilities, spanning architecture, development, deployment, and production operations. You will own parts of the core API, data processing and ETL pipelines, datalake, graph, container orchestration, and cloud infrastructure. The role is accountable for the performance, scalability, and uptime of several services and contributes to product launches and platform stability. Horizon3 is a fast-growing cybersecurity company whose NodeZero platform provides production-safe autonomous penetration testing and assessment operations across internal, external, cloud, and hybrid environments. The company describes itself as fully remote, with possible travel of up to 5%. The role requires US-person status for interviewing and eligibility to obtain and successfully secure a US Federal Security Clearance as a condition of employment.

Requirements

Bachelor’s degree in Computer Science, Computer Engineering, or a related field.
At least 7 years of professional software engineering experience using modern object-oriented or functional languages such as Python, Java, Go, Scala, C++, or TypeScript.
Experience building and operating workflow orchestration or distributed task-processing systems in production, such as Prefect, Temporal, Airflow, or Celery.
Hands-on experience designing and building high-throughput data processing systems and ETL pipelines.
Experience building applications on cloud platforms such as AWS, Azure, or GCP and using container technologies such as Docker and Kubernetes.
Ability to own and manage concurrent initiatives, with sound prioritization and time management.
Self-driven ability to conceive and implement solutions independently and collaboratively.
Reliability mindset for distributed work, including designing for retries, partial failure, and recovery, and methodically debugging asynchronous systems.
Strong analytical and problem-solving skills, clear communication, and attention to detail.
Operational ownership mindset and care for how code behaves in production.
Strong technical writing skills for design documents, runbooks, and API documentation.
Effective collaboration with designers, developers, and product managers.
Must be a US person to interview for this role and eligible for and able to successfully secure a US Federal Security Clearance as a condition of employment.

Nice To Haves

Deep Kubernetes experience, including managing deployments and clusters and troubleshooting production workloads.
Experience with durable-execution or workflow engines such as Temporal or 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, using tools such as Datadog, Prometheus, or OpenTelemetry.
Systems engineering and architecture experience with datalakes and related cloud services.
Experience building platform capabilities or internal tooling used by other engineering teams.
Experience in cybersecurity or with attack-surface and vulnerability data.
Strong desire to learn new technologies in a fast-paced Agile environment.

Responsibilities

Design, build, and maintain features in the core Python API, focusing on performance, correctness, and maintainability.
Design, build, and operate workflow orchestration for large-scale, long-running workloads, including scheduling, retries, idempotency, state management, and failure recovery.
Build orchestration that scales across concurrent workflows and provides visibility into progress, failures, and throughput.
Read, understand, optimize, or safely refactor complex SQL in production.
Build and operate high-throughput data processing and ETL pipelines that transform raw assessment data into reliable, queryable datasets.
Contribute to AWS datalake architecture, including storage layout, partitioning, schema evolution, and query performance.
Deploy and manage services on Kubernetes and participate in cluster operations, release management, and capacity planning.
Develop and extend GraphQL and graph-based APIs for exploring complex data relationships.
Own observability, uptime, and scalability of services, including metrics, tracing, alerting, and on-call participation.
Partner with frontend engineers, product managers, and designers to translate backend capabilities into clear, responsive user experiences.
Contribute to systems architecture decisions and write design documents that build shared understanding.
Collaborate with frontend team members to present data clearly and improve the product user experience.