Software Systems Engineer with Security Clearance

Apex Systems is seeking a highly motivated Software Systems Engineer to join our team in support of a mission-critical national security program. In this role, you will work closely with warfighters, government stakeholders, systems engineers, software developers, and cybersecurity engineers to design, integrate, and sustain complex software-intensive systems. You will support the full systems engineering lifecycle—from requirements definition and architecture through integration, test, deployment, and operations. This position is Onsite in Reston, VA. Responsibilities

• Perform systems engineering for software-intensive systems, including requirements analysis, functional decomposition, interface definition, and architecture development. • Elicit, document, and manage system and software requirements in collaboration with warfighters, mission stakeholders and development teams. • Develop and maintain system architectures, data flows, and technical baseline documentation (e.g., ICDs, design descriptions, CONOPS). • Support software integration troubleshooting and issue resolution across multiple components and environments. • Participate in and/or lead technical reviews (SRR, PDR, CDR, TRR) and provide technical input to decision-makers. • Work with software development teams using Agile and DevSecOps practices; support backlog refinement, sprint planning, and acceptance criteria definition. • Define and support verification and validation (V&V) activities, including test planning, test case development, and requirements traceability. • Collaborate with cybersecurity, infrastructure, and operations teams to ensure solutions meet performance, security, and availability requirements. • Support risk management, issue tracking, and configuration management of system baselines. • Prepare and deliver technical briefings, status reports, and engineering artifacts to both technical and non-technical audiences, including government customers. Qualifications
• Active TS/SCI clearance is required at the time of hire. • Bachelor’s degree in Computer Science, Computer Engineering, Systems Engineering, or a related technical discipline; • Additional years of relevant experience may be considered in lieu of a degree per contract guidelines. • 5+ years of experience in systems engineering and/or software engineering on complex, software-intensive systems. • Demonstrated experience with: o Requirements development, analysis, and management (e.g., DOORS, Jama, JIRA, or similar). o Development of system-level designs, architecture diagrams, and interface control documents. o Strong understanding of software development lifecycles (SDLC) and systems engineering processes (e.g., INCOSE, ISO, or DoD/IC standards). o Conducting or supporting **system integration and test** activities in lab or operational environments. o Excellent technical communication skills (written and verbal), including the ability to synthesize complex technical topics for diverse audiences. o Proven ability to work onsite in a classified environment, collaborating closely with customer and contractor teammates. Desired Qualifications
• Master’s degree in a relevant technical field (CS, CE, SE, EE, etc.). • Experience supporting DoD or Intelligence Community (IC) programs. • Experience with: o Cloud environments** (AWS, Azure, or government cloud variants). o Microservices, containerization, and orchestration** (Docker, Kubernetes). o DevSecOps pipelines and CI/CD tools (GitLab, Jenkins, Nexus, SonarQube, etc.). o Model-Based Systems Engineering (MBSE) tools and approaches (Cameo, MagicDraw, SysML). o Familiarity with zero trust, cybersecurity controls (NIST 800-53, RMF), and secure software design principles. o Experience defining and maintaining Interface Control Documents (ICDs) and data models for distributed systems. o Relevant certifications (e.g., INCOSE CSEP, AWS/Azure certifications, SAFe, PMP, or security-related certs such as Security+ if applicable to contract).