Senior Backend Engineer, Data & App Platform

Get to Know Us Horizon3 http://Horizon3.ai 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 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. DESIRED SKILLS - 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). Compensation and Values At 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. In accordance with various State’s transparency regulations, we provide the following salary range information for this position: - Base salary range: $199,750 - $235,000 annually. The exact salary will be determined based on the selected candidate’s location, qualifications, experience, and relevant skills. - Additional compensation: All full-time roles are eligible for an equity package in the form of stock options. Perks of Horizon3 http://Horizon3.ai - Inclusive Team: We value diversity and promote an inclusive culture where everyone can thrive. - Growth Opportunities: Be part of a dynamic and growing team with numerous career development opportunities. - Innovative Culture: Work in a collaborative environment that encourages creativity and out-of-the-box thinking. - Remote Work: We are a 100% remote company. Enjoy the flexibility to work in the way that supports you and brings out your best. - Competitive 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. You Belong Here Horizon3 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. Our 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. We 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. Other Duties 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. Application Note 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.