Software Engineer, Back-End (Pentest Platform)

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 assessmen...

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” sec...

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

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.
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.

Minimum of 4+ years of experience in software engineering or a similar role.
Proficiency in Python and/or Go, including experience with large-scale codebases.
Production experience with relational databases (PostgreSQL) — schema design, migrations, and query performance at scale.
Experience building and operating services in AWS or a comparable cloud, with containers and orchestration (Docker, Kubernetes).
Hands-on experience with observability tooling (Datadog, OpenTelemetry, or similar) in production.
Bachelor's degree in Computer Science, Computer Engineering, or related field, or equivalent practical experience.
Production experience with event-driven architectures or streaming platforms (Kafka, Kinesis, Flink, or similar)
Experience with designing distributed systems at scale, AWS a bonus.
Experience migrating a meaningful system from batch to streaming, or decomposing a monolith into services, while it stayed live for customers.
Graph database experience (Neo4j) and graph data modeling and SQL.
Background in cybersecurity, pentesting, or vulnerability management.
Experience with data-at-rest and in-transit encryption patterns (envelope encryption, KMS).