Senior Backend Engineer, Integrations at Horizon3.ai in US, Remote

Get to Know Us

Horizon3 is a fast-growing, remote cybersecurity company dedicated to the mission of enabling organizations to proactively find and 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 ITOps/SecOps teams, consulting pentesters, and MSSPs and MSPs.

We are a fusion of former U.S. Special Operations cyber operators, startup engineers, and formerly frustrated cybersecurity practitioners. We're committed to helping solve our common security problems: ineffective security tools, 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.

What You'll Do

You'll be joining the Platform Integration Team (PIT Crew) — a high-impact group whose mandate is critical to the scalability and extensibility of the NodeZero platform. The PIT Crew's mission is to transform Horizon3's APIs and integrations from a collection of one-off vendor connectors into a consistent, documented, permission-aware platform. You'll build the systems that let customers connect NodeZero to the tools they already rely on across the security and IT ecosystem.

This is a senior individual contributor role. You'll lead through technical judgment, cross-functional partnership, and high-quality execution — owning significant pieces of platform infrastructure while helping set the standard for the team.

In this role, you will:

• API Platform: evolving our internal GraphQL-federated API into a first-class, customer-facing product — with permissions, multi-account scoping, versioning, schema evolution, and documentation.

• Integration Platform: building and operating a shared Integration Router so new connectors can be configured and declared rather than built from scratch, with reusable authentication, health checks, and workflow execution.

• Security-Tool Integrations: shipping and maintaining integrations with the tools customers already use — CrowdStrike, Splunk, ServiceNow, Jira, Palo Alto, SentinelOne, and others in the SIEM, EDR, and ticketing ecosystem.

• MCP Platform: expanding our customer-facing MCP server and agentic workflow capabilities across US, EU, and Australia production environments, enabling customers to build their own AI-powered workflows atop NodeZero data.

• You'll also share on-call responsibility for a substantial production-observability footprint (Datadog, Kafka-triggered services, multiple environments), meaning you're not just shipping integrations — you're operating them.

What You'll Be Responsible For

• Design and implement backend APIs in GraphQL — including federated subgraph development, schema evolution, and multi-account query scoping for MSSP and multi-subsidiary customers.

• Build and extend the Integration Router: connector libraries, workflow configuration, secrets management, vendor adapters, and Kafka-triggered dispatch services.

• Own production reliability for API and integration services: monitoring, alerting, deployment, vendor API drift, rate limits, retries, and safe failure handling.

• Contribute to the MCP platform and OAuth proxy layer, including tool authentication and agentic workflow support.

• Contribute production code that sets the standard for design quality, code quality, and operational rigor.

• Collaborate with frontend engineers, product managers, and security-domain teams (particularly the Pentest Data Platform) to deliver integrated customer experiences.

• Mentor junior and mid-level engineers on the team as it scales.

What You'll Bring

• Ability to own and manage concurrent initiatives, with strong judgment in prioritization and time management.

• Self-directed and driven — capable of conceiving and implementing solutions independently and as part of a team.

• A strong desire to continuously learn new technologies in a fast-paced Agile environment.

• Excellent analytical and problem-solving skills, with attention to detail and a high bar for quality.

• Strong technical documentation ability to support an external developer audience.

• Effective communication and collaboration across engineering, product, and design.

• Interest in mentoring junior and mid-level engineers as the team grows.

Required Education / Experience

• Bachelor's Degree in Computer Science, Computer Engineering, or a related field.

• 7+ years of professional software engineering experience using modern object-oriented or functional languages (Python, Go, TypeScript, Java, Scala, C++, etc.).

• Experience building production applications on cloud platforms (AWS, Azure, GCP) using Docker and Kubernetes.

What Sets You Apart

• Expert proficiency in SQL, and experience with relational (PostgreSQL) and graph (Neo4j) database architectures.

• Hands-on experience building GraphQL backends, including federated graph architectures and schema evolution patterns.

• Experience designing and operating public API platforms — versioning, developer documentation, permission models, and multi-tenant access.

• Experience building or operating an integrations platform with reusable connector patterns, event-driven workflows (Kafka or similar), and asynchronous execution.

• Familiarity with OAuth/OIDC, service accounts, or machine identity patterns for programmatic API access.

• Experience integrating with third-party security or IT platforms — SIEMs, EDR tools, ticketing systems (e.g., CrowdStrike, Splunk, ServiceNow, Jira, Palo Alto), or workflow automation platforms.

• Experience with MCP, agentic frameworks, or other tool-protocol ecosystems.

• Production reliability experience: observability tooling (Datadog or similar), on-call ownership, vendor API drift handling, and safe failure design.

• Experience with customer-facing developer surfaces: CLI tooling, SDKs, or developer portals.

Perks of Horizon3

• 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.

• Hybrid & 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.

• 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.

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: $170,000 - $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.

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, 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.