Senior Backend Engineer, External

Get to Know Us Horizon3 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 As a Senior Backend Engineer on the External Attack team, you'll contribute to the full set of backend services that power NodeZero's external pentesting capabilities, from architecture and development through deployment and production operations. You'll own parts of our core API, data processing and ETL pipelines, datalake, graph, along with the container orchestration and cloud infrastructure beneath it all. You'll be accountable for the performance, scalability, and uptime of several of these services, and you'll be a key contributor to user-facing product launches and platform stability. Responsibilities - Design, build, and maintain features in our core Python API, with a focus on performance, correctness, and maintainability. - Design, build, and operate workflow orchestration for large-scale, long-running workloads using tools such as Prefect or Temporal, including scheduling, retries, idempotency, state management, and failure recovery. - Build orchestration that scales reliably across many concurrent workflows, with clear visibility into progress, failures, and throughput. - Comfort reading and untangling unfamiliar, complex SQL, and the judgment to optimize or refactor it safely in production. - Build and operate high-throughput data processing and ETL pipelines that turn large volumes of raw assessment data into reliable, queryable datasets. - Contribute to datalake architecture on AWS, including storage layout, partitioning, schema evolution, and query performance. - Deploy and manage services on Kubernetes, and take part in cluster operations, release management, and capacity planning. - Develop and extend GraphQL and graph-based APIs that let product components and customers explore complex relationships in their data. - Own the observability, uptime, and scalability of the services you build, including metrics, tracing, alerting, and on-call participation. - Partner with frontend engineers, product managers, and designers to turn backend capabilities into a clear, responsive user experience. - Contribute to systems architecture decisions and write design docs that help the team move quickly with shared understanding. - Collaborate with frontend team members to present data in a clear and user-friendly format, enhancing the product's user experience. What You’ll Bring - The ability to own and manage concurrent initiatives, with sound judgment in prioritization and time management. - A self-driven approach: you can conceive and implement solutions on your own and with a team. - A reliability m