Senior Full Stack Software Engineer

ABOUT DEFCON AI RESILIENCE IN THE FACE OF DISRUPTION. DEFCON AI is an insights company that leverages artificial intelligence, mathematical optimization, data analytics, and software engineering for resilient optimization of complex systems. In today’s dynamically changing world, DEFCON AI’s technology aligns outcomes with operational goals, better decision making, and empowers customers to anticipate assess, and mitigate the impacts of disruptions. About the Role We’re hiring a Senior Full Stack Software Engineer to design, build, and scale modern web applications end-to-end. You’ll work across frontend UI, backend services, APIs, asynchronous processing, and data layers—shipping features that are reliable, secure, and built to last. This is a senior individual contributor role with real autonomy and real impact. You’ll have end-to-end ownership of features and meaningful input into technical decisions, quality standards, and delivery practices working in a remote-first environment. Core Tech Stack: Frontend : React 19, TypeScript, Vite-based React apps, Tailwind CSS, SignalR Backend: .NET 9 (C#), Minimal APIs, Entity Framework Core Async Processing: RabbitMQ, Redis (for scale-out and caching) Data and Storage: PostgreSQL, Amazon S3 What You’ll Do Shape the product architecture end-to-end. You’ll design and ship modular .NET services and modern React frontends that stay fast, reliable, and elegant across a wide range of real-world customer environments. Own the data foundation. You’ll design high-performance PostgreSQL schemas and craft EF Core queries that serve as the source of truth for business logic, permissions, and RBAC—balancing correctness, clarity, and scale. Engineer for performance at scale. You’ll build smart caching layers with Redis and leverage S3 for large artifacts, keeping our Web Gateway lean, responsive, and built to grow. Drive technical direction through RFCs. You’ll author and collaborate on design proposals that define data contracts and API boundaries, making our .NET platform and Python-based solver runners work together seamlessly. Ship with product and design, not in a silo. You’ll partner closely with product and design to turn real customer problems into thoughtful technical solutions—and deliver them in tight, iterative releases. Use AI as a force multiplier (responsibly). You’ll leverage tools like Claude Code and GitHub Copilot/Cursor to move faster and refactor with confidence, while keeping security, quality, and maintainability non-negotiable. Hold the quality bar high. You’ll help set the standard through great code reviews, automated testing, and pragmatic engineering practices that keep the codebase a joy to work in. What We’re Looking For (Required) Production experience with hash-chained audit, Merkle-tree sealing, and cross-language evidence parity (C# + Python) Depth in cryptographic evidence pipelines — HMAC integrity, signed checkpoints, chain continuity verification Fluency in PostgreSQL transactional guarantees for audit writes, advisory-lock coordination patterns Prior work on ATO-evidence-bearing audit implementations (DoW, fintech regulatory audit, HIPAA-equivalent scale) Ability to architect AWS KMS integration with envelope encryption; HSM (PKCS#11) integration familiarity Nice to Have (Preferred) Prior DoW / federal ATO submission experience NIST SP 800-53 AU family control implementation experience Prior DoW ATO experience on CDS integrations, familiarity with Radiant Mercury / ISSE Guard / EverFox / Forcepoint WebShield, knowledge of the ISSE approval workflow. Other Qualifications Analytical Aptitude: Possess keen analytical and problem-solving skills, coupled with the capability to understand complex software challenges and collaborate toward viable solutions. Effective Communication: Skilled in distilling technical complexities into comprehensible terms for varied audiences. Adaptive Nature: Resilience and adaptability in the face of an ever-changing tech landscape, w