Senior Backend Engineer, Defensive Agent
Horizon3 AI6 hours ago
Remote, United StatesSenior
Base Salary
$199k - $235k/yr
Responsibilities
- Build and own a durable, resumable agent execution runtime with checkpointing, idempotency, cancellation, and timeouts.
- Design a versioned, schema-validated, per-tenant agent tool registry with server-side authorization.
- Build connector integrations for EDR, firewall, identity, SIEM, and cloud IAM control planes.
- Implement simulation, approval gates, staged rollout, rollback, blast-radius classification, and immutable tenant audit trails for production changes.
- Extend tenant isolation for agent write actions through execution boundaries, egress control, quotas, and protection against cross-tenant leakage.
- Develop ETL and GraphQL product features for agent context, run history, remediation state, and research datasets.
- Instrument agent runs with distributed tracing, cost and token accounting, and diagnostic tooling.
- Partner with AI researchers, attack engineers, and product teams to move capabilities from prototype to production.
Requirements
- Bachelor’s degree in Computer Science, Computer Engineering, or a related field.
- 7+ years of professional software engineering experience using modern object-oriented or functional languages such as Python, Go, Scala, C++, or TypeScript.
- Experience building applications on AWS, Azure, or GCP using Docker and Kubernetes.
- Expert proficiency in SQL.
- Experience designing and operating production distributed systems involving asynchronous workflows, queues, retries, idempotency, and partial failure.
- Track record of shipping and operating production services, including on-call ownership.
- Preferred experience with agentic or LLM-backed systems, durable execution or workflow engines such as Temporal, and multi-tenant platforms with hard isolation requirements.
- Preferred experience integrating third-party APIs, security control planes, PostgreSQL, Neo4j, GraphQL, Datadog, Prometheus, Grafana, and distributed tracing.
- Awareness of prompt injection and untrusted-input handling in agent systems.
Benefits
- Hybrid and remote work models depending on role and location, including the Chicago office where some roles require regular in-office presence.
- Health, vision, and dental insurance for employees and families.
- Flexible vacation policy and generous parental leave.
- Equity package in the form of stock options for all full-time roles.
- Inclusive culture, growth opportunities, and collaborative innovation environment.
Tech Stack
AWSAzureC++DatadogDockerGoGoogle Cloud PlatformGrafanaGraphQLKubernetesNeo4jPostgreSQLPrometheusPythonScalaSQLTypeScript
Categories
About Horizon3 AI
Horizon3 AI builds NodeZero, a proactive security platform that autonomously performs penetration testing and validates attack paths across on‑prem, cloud, and hybrid environments. The company sells its software by subscription to security and IT teams at enterprises and government agencies, helping prioritize and verify fixes. Founded in 2019 and headquartered in San Francisco, it is privately held and serves customers across regulated industries and the public sector.