About the job
**This is a direct hire opportunity for our esteemed client based in Seattle, Washington. U. S. work authorization is mandatory; sponsorship will not be provided.**
We are seeking a talented Software Engineer (Endpoint Systems) with a robust background in developing endpoint-native software across macOS, Windows, and/or Linux platforms. The ideal candidate will possess a deep understanding of the workstation networking stack. In this role, you will contribute to the development of crucial components of a runtime layer that operates between the OS and user-space applications, effectively capturing and influencing network and system behavior in real time.
Key Responsibilities
Design and maintain cross-platform endpoint applications (macOS, Windows, Linux)
Create systems that intercept, analyze, and control network and application behavior
Engage in low-level systems programming (e.g., macOS Network Extension, Windows/Linux equivalents)
Work closely with the OS layer (user-space, system APIs, potentially kernel-adjacent components)
Implement logic for policy enforcement, traffic inspection, and action gating
Collaborate with security, AI, and infrastructure engineers to comprehend agent workflows and associated risks
Optimize for performance, reliability, and low-latency interception
Required Qualifications
Core Requirements
3–6 years of experience in application or systems development
Strong programming skills in one or more of the following: Go, Rust, C/C++, or Python
Proven experience in developing software for at least one desktop OS (macOS, Windows, or Linux)
Endpoint / Systems Experience
Familiarity with OS-level APIs (file system, processes, IPC) and background services, daemons, or agents
Experience with system extensions, drivers, or low-level hooks is a plus
Networking Expertise (Key)
Solid understanding of the TCP/IP stack, sockets, HTTP/S, and network interception patterns (proxies, packet inspection, hooks)
Experience with traffic inspection, filtering, or routing as well as endpoint/network security tools (EDR, firewall, proxy, etc.)
Preferred Skills
Experience with security products or observability tools
Familiarity with AI/LLM tooling or agent frameworks
Experience in building cross-platform applications is highly desirable

