Staff Software Engineer, Backend MSSP

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. What You’ll Do As a Staff Backend Engineer on the MSSP & TRPM team, you’ll provide hands-on technical leadership for the NodeZero capabilities that enable partners to manage services across many customer environments. You’ll shape architecture for multi-tenant workflows, account hierarchies, delegated administration, client and sub-client management, and asset allocation or deprecation. You’ll guide designs that preserve tenant boundaries and give partners reliable ways to administer their customer relationships. Working across Product and Engineering, you’ll lead complex initiatives while remaining accountable for implementation quality and production outcomes. Responsibilities - Set technical direction for partner and multi-tenant platform services, including account hierarchies, tenant isolation, delegated administration, and partner workflows. - Lead architecture and implementation of complex capabilities for client and sub-client management, asset allocation or deprecation, and partner administration. - Define patterns for secure data boundaries, API design, reliability, observability, and operational readiness. - Remain hands-on in complex technical work and help teams make decisions when requirements or tradeoffs are ambiguous. - Partner with Product, customer-facing teams, and adjacent engineering groups to align platform capabilities with partner needs. - Mentor engineers through design reviews, code reviews, pairing, and technical documentation. - Own complex production issues and drive improvements that strengthen service reliability and prevent recurrence. What You’ll Bring - Ability to lead broad technical initiatives, establish direction, and build alignment across teams. - Strong judgment around tenant isolation, security, data integrity, reliability, and customer impact. - Clear communication and technical writing, including the ability to explain architecture and tradeoffs to both technical and non-technical partners. - A mentoring mindset and commitment to raising engineering practices across the organization. - Hands-on ownership of production services, including operational follow-through and continuous improvement. Required Education / Experience - Bachelor’s degree in Computer Science, Computer Engineering, or a related field, or equivalent practical experience. - 8+ years of professional software engineering experience, including deep experience with backend systems and APIs. - Track record of leading architecture or technical direction for production multi-tenant, platform, or di