Software Engineer, Back-End (Pentest Platform)

Get to Know Us
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 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.
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.
What You'll Do
The Pentest Data Platform team owns how NodeZero turns raw pentest telemetry into the findings, attack paths, reports, and insights our customers act on. As Horizon3 has grown in both customer count and customer size. Our team is taking on the largest architectural change in Horizon3's history: a ground-up rework of pentest data processing from a batch system into a real-time, event-driven microservice architecture.
We're laying the foundation to make Horizon3 best-in-class for enterprise pentests at scale — handling hundreds of thousands of hosts and streaming findings as they're discovered. Customers go from waiting weeks for insights to getting them in hours, fundamentally transforming how the entire product suite feels to use.
This work demands platform engineering to build the infrastructure foundation, paired with deep cybersecurity domain understanding to translate years of batch-centric business logic into real-time processing. As a Senior Engineer on this team, you will be one of the people we trust to own a hard piece of that rework end to end.
In this role, you will:
- Design, build, and operate event-driven services that process pentest data in real time event streaming, stream processing, storage, schema evolution, and replayable processing.

- Take ambiguous, high-impact problems from "we need to solve this" through design, implementation, rollout, and long-term operation, without needing the path drawn for you.

- Help solve challenges around converting large per-pentest datasets, and converting that to a cohesive story over time. Tackling challenging problems such as understanding when two hosts are the same even with different IP addresses.

- Translate existing batch-era logic — finding enrichment, attack path analysis, host and identity correlation, reporting — into streaming-friendly designs without regressing fidelity.

- Solve genuinely hard distributed systems problems at scale: breaking out a half-decade hold monolithic data-storage for an engineering org that is rapidly growing in both scale of customers and number of engineering teams.

- Set a high bar for operational excellence — SLOs, instrumentation, alerting, on-call, and incident response, as this system becomes central to every pentest Horizon3 runs.

- Raise the technical bar around you through design reviews, technical writing, clear API contracts with neighboring teams, and durable decision records. Interface with other platform teams and attack-engineering teams.

Required Education/Experience
- Minimum of 4+ years of experience in software engineering or a similar role.

- Proficiency in Python and/or Go, including experience with large-scale co