Software Engineer - Runtime

About XageCyberattacks on critical infrastructure, government, and private enterprises are at an all time high – and only growing more urgent by the day. Xage is a global leader in zero trust access and protection at the forefront of solving this pressing issue. We are pioneering a secure tomorrow by empowering organizations worldwide to connect anyone to anything, while delivering unparalleled defense against every cyber threat.We have built tremendous momentum across governments and commercial enterprises around the world, and it’s just the beginning. Recognized by Forbes as one of America’s Best Startup Employers, Xage prioritizes creativity, collaboration, and innovation in pursuit of our mission. We are headquartered in Palo Alto, CA and have global teams across North America and EMEA.We’re passionate about solving problems that have positive, real-world consequences for the lives of everyday people. We hope you’ll join us in the fight against cyberattacks and safeguarding critical infrastructure.About the RoleWe are seeking a Senior Runtime & Systems Engineer to build the runtime security layer powering Agent Sentry, the enforcement plane of our Zero Trust AI Gateway platform.While traditional AI security focuses on inspecting prompts and responses, Agent Sentry provides runtime visibility and control for autonomous AI agents wherever they execute—across Linux, macOS, and Windows environments. It monitors and governs agent activity including prompts, tool calls, API requests, generated outputs, filesystem access, process execution, shell/PowerShell activity, and agent-to-agent communications.In this role, you will design and productionize OS-level interception, runtime monitoring, sandboxing, identity controls, and tamper-resistant audit infrastructure to secure AI agents operating across enterprise environments.You will work across systems engineering, operating system security, distributed infrastructure, and zero-trust architecture to build the foundation for secure autonomous AI deployments.Key ResponsibilitiesCross-Platform Runtime Security & SandboxingBuild runtime monitoring and interception across Linux, macOS, and Windows using technologies such as eBPF, Endpoint Security Framework, ETW, and OS-level security APIs.Capture and analyze process execution, filesystem activity, network events, and agent behaviors.Develop secure agent isolation using containers, OS-native sandboxes, and lightweight virtualization (containerd, runc, Firecracker, Wasm).Design runtime controls to prevent unauthorized agent actions and reduce security risks.Agent Identity, Lifecycle & Policy EnforcementBuild agent identity infrastructure supporting registration, authentication, cryptographic attestation, short-lived credentials, and automated credential rotation.Develop lifecycle governance for agent onboarding, authorization, monitoring, and decommissioning.Integrate runtime telemetry with policy engines to enable real-time access decisions, inline enforcement, and automated containment.Required Qualifications & Expertise3-5+ years building production security, systems, or infrastructure software.Strong programming skills in Go, C/C++ with experience developing high-performance, security-critical systems.Experience with OS internals, runtime security, kernel instrumentation, security telemetry, sandboxing, or container isolation.Strong understanding of host security, privilege escalation, runtime exploitation, and endpoint threats.Experience with eBPF, Linux kernel development, Windows Kernel, or macOS security frameworks.Preferred QualificationsExperience building EDR/XDR, runtime security, endpoint protection, or cloud workload security platforms.Experience securing AI agents, LLM applications, or autonomous systems.Familiarity with Kubernetes security, service mesh, and cloud-native security.Familiarity with zero-trust architectures, identity systems, PKI, mTLS, SPIFFE/SPIRE, OAuth/OIDC, and credential management.Perks Salary Range: $140,000 – $170,000 p/yr + EquityFull health, dental, vision insuranceWe will process visa transfers and immigration Work with founders and executives closely and participate in all aspects of company buildingEarly stage opportunity in a massive sized market with proven traction and growing rapidly