Full Stack Software Engineer III (Full Scope Poly) with Security Clearance

Shadowgate Partners is seeking a Senior Full Stack Software Engineer for a Client. We are seeking a high-caliber full-stack engineer who thrives in a rapid development and deployment environment. A key focus of this role is reacting swiftly to emergent mission opportunities—designing and deploying new capabilities under tight timeframes. You will provide end-to-end support to a cross-functional team automating critical solutions across the entire software stack, including user interfaces, middleware, databases, analytics, and cloud architectures. Collaboration is essential as you modernize legacy infrastructure and scale future capabilities, using cutting-edge automation and AI-assisted development tools to accelerate mission success. Key Responsibilities • Develop end-to-end full-stack solutions—including user interfaces, REST middleware, databases, and analytics—in support of the team's mission.
• Automate new opportunities and capabilities.
• Maintain and update existing front-end interfaces using JavaScript, HTML/CSS, Bootstrap, and jQuery, while preparing to migrate future front-ends to modern UI libraries such as React, Angular, or Vue.
• Optimize existing back-ends using Python, Asyncio, and Pandas, and occasionally update legacy Java Map/Reduce and analytics.
• Manage and deploy services within existing infrastructure environments using Docker, Nginx, and GitLab CI/CD, while planning expansions into additional cloud and hyper-converged environments.
• Leverage AI-assisted development tools such as Claude Code, Codex, and Opencode to accelerate delivery and improve team velocity. Required Qualifications • Production-grade software development experience in Python and JavaScript to build robust, full-stack architectures.
• Knowledge of developing user interfaces, REST middleware, databases, and analytics within a cross-functional team.
• Experience with collaborative development workflows and a strong track record of teamwork and communication.
• Familiarity with Git-based version control systems and continuous integration pipelines. Preferred Qualifications • Experience using and customizing AI-assisted development tools (Claude Code, Codex, Opencode, etc.) through advanced configurations such as Skills and Memory.
• Familiarity with modern UI libraries (React, Angular, Vue) and cloud-based hosting environments such as AWS.
• Experience with infrastructure expansion and deployment using tools such as Docker, Nginx, and GitLab CI/CD. Experience & Education Minimum 12 years of relevant experience with a B.S. in a technical discipline, or 4 additional years of experience in place of a B.S. Clearance Level This position requires an active Top Secret/SCI clearance with a Full Scope Polygraph. Applicants must be U.S. citizens and must hold, or be able to reinstate, the required clearance and polygraph prior to start. Clearance eligibility must be maintained throughout the duration of employment. Salary & Benefits $260,000 – $285,000 per year, plus an additional 25% in fully and immediately vested employer 401(k) contributions. In addition to the base salary and 401(k) contributions listed above, our Client offers a comprehensive benefits package including medical, dental, and vision coverage, paid time off and holidays, life and disability insurance.