{"id":3717038,"url":"https://alion.io/job/horizon3-senior-full-stack-engineer-autonomous-defense","title":"Senior Full-Stack Engineer, Autonomous Defense","company":{"id":3088,"name":"Horizon3","domain":"horizon3.ai","url":"https://alion.io/company/horizon3","size_band":"1001-5000","is_staffing_agency":false,"employer_type":"direct","is_intermediary":false,"listed_via":null,"ats_vendor":"Ashby","truth_index":{"grade":"B","score":81,"open_postings":25,"ghost_share":0,"stale_share":0.76,"repost_share":0,"time_to_fill_p50_days":36,"computed_at":"2026-11-04T06:34:25Z"}},"role":"Backend","role_family":"Backend","seniority":"senior","employment_type":"full_time","work_mode":"remote","remote_scope":"stated_countries","remote_scope_basis":"posting_text","remote_working_hours":null,"hiring_geo_confidence":"structured","locations":[],"countries":[],"hiring_countries":["US"],"hiring_countries_total":1,"salary":{"min":195000,"max":235000,"currency":"USD","period":"year","gross":null,"usd_annual":235000},"salary_estimate":null,"experience_years_min":7,"visa_sponsorship":false,"relocation_package":false,"has_equity":true,"technologies":[{"name":"Apollo","optional":false},{"name":"AWS","optional":false},{"name":"Azure","optional":false},{"name":"C++","optional":false},{"name":"Crowdstrike","optional":false},{"name":"Datadog","optional":false},{"name":"Docker","optional":false},{"name":"ETL/ELT","optional":false},{"name":"GCP","optional":false},{"name":"Go","optional":false},{"name":"Grafana","optional":false},{"name":"GraphQL","optional":false},{"name":"IAM","optional":false},{"name":"Kubernetes","optional":false},{"name":"LLM","optional":false},{"name":"Microsoft Defender","optional":false},{"name":"Neo4j","optional":false},{"name":"PostgreSQL","optional":false},{"name":"Prometheus","optional":false},{"name":"Python","optional":false},{"name":"React Query","optional":false},{"name":"Scala","optional":false},{"name":"SentinelOne","optional":false},{"name":"SIEM","optional":false},{"name":"SQL","optional":false},{"name":"TypeScript","optional":false},{"name":"WebSockets","optional":false},{"name":"JavaScript","optional":true},{"name":"React.js","optional":true}],"status":"live","first_seen_at":"2026-11-03T20:32:13Z","employer_posted_date":"2026-11-03","last_verified_at":"2026-11-04T10:45:06Z","board_verified":true,"closed_at":null,"days_open":0,"trust":{"level":"ok","repost_count":null,"flags":[],"days_open":0},"description":"Get to Know Us\nHorizon3 is a fast-growing, remote cybersecurity company dedicated to the mission of enabling organizations to proactively find, 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 IT Ops/SecOps teams, consulting pentesters, and MSSPs and MSPs.\nWe are a fusion of former U.S. Special Operations cyber operators, startup engineers & operators, and formerly frustrated cybersecurity practitioners. We're committed to helping solve our common security problems: ineffective security tools and 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.\nWhat You'll Do\nAs a Senior Full-Stack Engineer on the Autonomous Defensive team, you'll build the platform that NodeZero's defensive agents run on. Our AI researchers define what these agents should reason about, you build the systems that make that work in production, across thousands of customer tenants, without breaking anything.\nThat means real distributed systems problems, not glue code. They execute inside customer environments under tight isolation, credential, and egress constraints. And when an agent proposes a change in production, the platform has to be able to simulate it, stage it, gate it on approval, roll it back, and prove after the fact exactly what happened and on whose authority.\nIt also means the interfaces that sit on top of all of that. Autonomous systems are only trusted to the extent that people can see what they did and intervene before they do it, and that burden lands on the front end. These surfaces are part of the product, not a thin layer over the API, and you'll own them end to end alongside the backend they talk to.\nThis is a platform role. You'll own the runtime, the tool layer, the orchestration, the connector framework, and the observability and UI that make agent behavior debuggable. We're looking for engineers with strong backend depth who are comfortable building the front end when the workflow demands it - not because it's beneath them, but because they understand the value of end-to-end delivery. You'll work closely with our AI researchers, but you are not being hired to tune prompts - you are being hired to build the substrate that makes their work shippable and safe.\nResponsibilities\nBuild and own the agent execution runtime: durable, resumable, long-running workflows with checkpointing, idempotent steps, cancellation, and timeouts at both the step and run level.\n\nDesign and implement the tool layer that agents act through - a registry with versioning, schema validation, per-tenant enablement, and authorization enforced server-side rather than by the model.\n\nBuild the connector framework for third-party security control planes (EDR, firewall, identity, SIEM, cloud IAM).\n\nImplement the safe-change pipeline: dry-run and simulation, blast-radius classification, approval gates for high-impact actions, staged rollout, rollback, and an immutable per-tenant audit trail.\n\nBuild the operator-facing front end in React and TypeScript, turning dense system state into interfaces a user can reason about and act on with confidence.\n\nBuild the client-side data and streaming layer that keeps those interfaces accurate against long-running, incrementally updating state, over WebSockets rather than polling.\n\nExtend NodeZero's tenant isolation model to agents that take write actions, covering execution boundaries, egress control, quotas, and cross-tenant leakage in caches, indexes, and logs.\n\nDevelop core product features in ETL and GraphQL to support data processing and retrieval for agent context, run history, and remediation state.\n\nBuild the ETL pipelines that turn pentest and remediation outcomes into the datasets our researchers train and evaluate against.\n\nInstrument everything. Distributed tracing across an agent run, cost and token accounting per tenant, and the tooling to answer \"why did the agent do that\" without guessing.\n\nPartner with AI researchers, attack engineers, and product to take capabilities from prototype to production, and feed platform constraints back into research direction early rather than late.\n\nRequired Education / Experience\nBachelor's Degree in Computer Science, Computer Engineering or related field.\n\n7+ yrs professional software engineering experience using modern object-oriented or functional languages (Python, Go, Scala, C++, TypeScript, etc).\n\nProven experience delivering backend APIs, especially GraphQL, and consuming them from a modern web stack.\n\nProduction experience with React, TypeScript, and modern CSS layout, with the judgment to build a usable interface for a complex workflow without a designer holding your hand.\n\nExperience building applications on cloud computing platforms such as AWS, Azure, GCP, using container technologies such as Docker and Kubernetes.\n\nExpert proficiency in SQL.\n\nDemonstrated experience designing and operating distributed systems in production: asynchronous workflows, queues, retries, idempotency, and partial failure.\n\nA track record of shipping and operating production services, including on-call ownership.\n\nWhat Sets You Apart\nExperience building agentic or LLM-backed systems in production\n\nExperience with a durable execution (such as Temporal) or workflow engine or having built equivalent checkpointing yourself.\n\nExperience building multi-tenant platforms with hard isolation requirements, workload identity, and short-lived credential brokering.\n\nExperience integrating a long tail of third-party APIs behind a normalized abstraction.\n\nFamiliarity with security control planes and their APIs - EDR (CrowdStrike, SentinelOne, Microsoft Defender), firewalls, SIEM, cloud IAM.\n\nExperience with database architectures including relational (PostgreSQL) and graph (Neo4j), and experience building GraphQL backends.\n\nExperience with client-side data and streaming patterns - React Query or Apollo, GraphQL subscriptions, WebSockets - against long-running, incrementally updating state.\n\nExperience building operator-facing or admin interfaces where density, auditability, and getting the destructive action right matter more than visual polish.\n\nExperience with observability tooling (Datadog, Prometheus, Grafana) and distributed tracing.\n\nAwareness of prompt injection and untrusted-input handling in systems where an agent consumes data from the environment it operates in.\n\nTravel Required\nWe are a fully remote company, and this job may require up to 5% of travel to be successful.\nCompensation and Values\nAt Horizon3, we believe that our people are our greatest asset, and our compensation philosophy reflects this core value. We are committed to fostering an environment where all employees feel valued, respected, and rewarded for their contributions. Our compensation structure is designed to be fair, competitive, and transparent, ensuring that every team member is recognized and compensated equitably across roles, levels, and locations.\nIn accordance with various State’s transparency regulations, we provide the following salary range information for this position:\nBase salary range: $195,000- $235,000 annually. The exact salary will be determined based on the selected candidate’s location, qualifications, experience, and relevant skills.\n\nAdditional compensation: All full-time roles are eligible for an equity package in the form of stock options.\n\nPerks of Horizon3\nInclusive Team: We value diversity and promote an inclusive culture where everyone can thrive.\n\nGrowth Opportunities: Be part of a dynamic and growing team with numerous career development opportunities.\n\nInnovative Culture: Work in a collaborative environment that encourages creativity and out-of-the-box thinking.\n\nHybrid & Remote Work: We embrace a mix of remote and hybrid work models depending on role and location, including our Chicago office, where some roles require regular in-office presence.\n\nCompetitive Compensation: We offer competitive salary, equity and benefits. Our benefits include health, vision & dental insurance for you and your family, a flexible vacation policy, and generous parental leave.\n\nYou Belong Here\nHorizon3 is not just an equal opportunity employer - we are a community that values diversity, equity, and inclusion as fundamental principles of our culture and success. We are dedicated to fostering a workplace where everyone feels welcome and respected, regardless of race, color, religion, sex, national origin, age, disability, veteran status, sexual orientation, gender identity or expression, genetic information, marital status, hair length or any other legally protected status by law.\nOur commitment to diversity and inclusion means we strive to attract, develop, and retain a workforce that reflects the varied communities we serve. We believe that diverse perspectives drive innovation and strengthen our ability to create cutting-edge cybersecurity solutions. At Horizon3, every team member is valued and supported in an environment that encourages personal and professional growth.\nWe welcome candidates from all backgrounds and experiences, and we encourage all qualified individuals to apply. Come be a part of Horizon3, where your unique contributions are recognized, and your potential is limitless.\nOther Duties\nPlease note this job description is not designed to cover or contain a comprehensive listing of activities, duties or responsibilities that are required of the employee. Duties, responsibilities, and activities may change at any time with or without notice.\nApplication Note\nIn any materials you submit, you may redact or remove age-identifying information such as age, date of birth, or dates of school attendance or graduation. 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