Note: The job is a remote job and is open to candidates in USA. Horizon3.ai develops NodeZero, a platform for autonomous penetration testing and security assessments. The Senior Backend Engineer will build and operate backend services for external penetration testing, including APIs, workflow orchestration, data pipelines, cloud infrastructure, and graph-based capabilities.

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

Skills

• 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 mindset for distributed work: you design for retries, partial failure, and recovery, and you debug asynchronous systems methodically
• A strong desire to keep learning new technologies in a fast-paced Agile environment
• Excellent analytical and problem-solving skills, clear communication, and attention to detail
• A bias toward operational ownership: you care how your code behaves in production
• Strong technical writing for design docs, runbooks, and API documentation
• Effective collaboration with designers, developers, and product managers
• Bachelor's Degree in Computer Science, Computer Engineering or related field
• 7+ yrs 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 (for example 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 such as AWS, Azure, GCP, using container technologies such as Docker and Kubernetes
• Only US persons can interview for this role due to security clearance requirements by our customer(s) and/or vendor(s)
• Employee must be eligible for and successfully secure a US Federal Security Clearance as a condition of employment
• 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 workflows that are resilient, observable, and easy to evolve
• Experience building GraphQL backends and working with graph databases
• A track record of owning observability, uptime, and scalability for production systems (for example Datadog, Prometheus, or OpenTelemetry)
• Systems engineering and architecture experience with datalakes and the cloud services around them
• Experience building platform capabilities or internal tooling that other engineering teams rely on
• Experience in cybersecurity or with attack surface and vulnerability data

Benefits

• Inclusive team and culture
• Numerous career development opportunities
• Collaborative environment that encourages creativity and out-of-the-box thinking
• Hybrid and remote work models depending on role and location, including the Chicago office; some roles require regular in-office presence
• Equity package in the form of stock options for all full-time roles
• Health, vision and dental insurance for you and your family
• Flexible vacation policy
• Generous parental leave

Company Overview