Staff Software Engineer, OTA Services

Horizon3 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 NodeZero™ 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.

We 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.

As a remote first company, we require minimum 25Mbps consumer grade broadband connection.

The Expert Engineer on the OTA Services team is the technical anchor for how NodeZero updates itself across thousands of customer deployments — without customer intervention, without downtime, and without introducing new vulnerabilities in the process. NodeZero runs as a container inside customer infrastructure. When a new image is ready, the OTA system has to find every deployed instance, negotiate the update, deliver it safely, validate it, and roll back gracefully if something goes wrong. Getting that right at scale, across diverse customer environments including air-gapped and restricted networks, is a genuinely hard systems problem.

This is a hands-on staff-level role. You will write production code, produce architecture designs, set the technical direction for update delivery and version management, and mentor P4 engineers on the team. The OTA Services team works in close partnership with the Image Build & Release team — your counterpart on the build side produces the artifacts you deliver. This role reports to the Client Platform Engineering Manager.

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• 8+ years of professional software engineering experience with deep specialization in distributed systems, remote update systems, or fleet management infrastructure

• Deep understanding of remote update system design — delivery protocols, version negotiation, delta delivery, health verification, and rollback semantics

• Experience designing rollout strategies for software deployed across heterogeneous, customer-managed environments — you understand the difference between a lab rollout and rolling something out to thousands of production deployments you don't control

• Strong proficiency in Go, Python, or Rust for systems-level infrastructure work

• Experience building software that operates in constrained or air-gapped environments — you know how to design delivery systems that don't assume good connectivity

• Deep understanding of Kubernetes — how deployments are managed, updated, and monitored in running clusters

• Experience with container image distribution: OCI artifacts, image manifests, layer caching, and registry protocol

• Strong understanding of mTLS, certificate lifecycle, and secure channel establishment for update delivery

• Track record of setting engineering standards that other engineers adopt — protocol designs, reliability requirements, and testing standards for distributed systems

• Ability to produce clear architecture documents and drive technical decisions across team boundaries (especially with the Image Build team that produces your input artifacts)

• Experience mentoring mid-level engineers through design review and code review

• Experience with Kubernetes operators or controller patterns — OTA delivery in Kubernetes environments often benefits from operator-style lifecycle management

• Background in cybersecurity or experience building software for regulated or high-security environments

• Familiarity with Fleet (or similar open-source fleet management tools) and where custom infrastructure is preferable

• Experience with signed artifact delivery and chain-of-custody verification end-to-end

We are a fully remote company, and this job may require up to 5% of travel to be successful.

Please 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.

In 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. You will not be penalized for redacting or removing this information.