Senior Backend Engineer MSSP

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. Node Zero has been adopted by organizations of all sizes, from small educational institutions to government agencies and Global 100 enterprises.

It is used by ITOps/Sec Ops 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.

You’ll be joining Growth & MSSP - the team that owns the foundational control plane governing what customers can access, what they've purchased, and how they're administered across Node Zero. If the Pentest Platform is the engine, Enterprise Platform is the operating model that determines who gets to use it and how.

The team's work spans licensing and entitlements, admin experience, provisioning, notifications, MSP/MSSP capabilities, and auditability. These aren't just internal systems - they're the services that directly shape how customers, administrators, and service providers experience Node Zero every day. Getting them right means building for correctness, consistency, and trust across a complex multi-tenant commercial model.

This is a senior individual contributor role. You’ll lead through technical judgment, careful system design, and reliable execution - owning significant pieces of platform infrastructure while contributing to a team that balances feature delivery with long-term platform investment and production health.

• Design and implement backend services that enforce licensing, entitlements, feature access, usage limits, and packaging rules consistently across Node Zero's product, APIs, and partner workflows.

• Build and evolve provisioning and onboarding workflows - account setup, entitlement propagation, and auto-provisioning that reliably activates customers without manual intervention.

• Develop admin experience infrastructure: user access controls, account settings, parent-child account relationships, and the RBAC/authorization patterns that make multi-tenant administration safe and auditable.

• Build MSP/MSSP capabilities - asset allocation, sub-client management, usage visibility, and reporting workflows that let service providers manage multiple customer environments at scale.

• Implement audit logging and event history systems that capture administrative, entitlement, usage, and account-level actions for support, compliance, and customer trust.

• Develop the notifications platform: usage warnings, consumption alerts, overage notices, product announcements, and other transactional and non-transactional communications.

• Operate these services in production - contributing to monitoring, runbooks, incident response, and support workflows for systems customers depend on daily.

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

• Collaborate with adjacent teams - Pentest Data Platform and the Platform Integration…