Senior Full Stack Software Engineer

About Us Red Cell Partners is an incubation firm building and investing in rapidly scalable technology-led companies that are bringing revolutionary advancements to market in three distinct practice areas: healthcare, cyber, and national security. United by a shared sense of duty and deep belief in the power of innovation, Red Cell is developing powerful tools and solutions to address our Nation’s most pressing problems. ABOUT DEFCON AI DEFCON AI is a modeling, simulation, and analysis (MS&A) company that provides cutting-edge technology solutions for generating operationally relevant insights for the next generation of logistics and mobility decision making. An AI- driven software incorporating an intelligent agent within a simulation environment — DEFCON is the next driving force in defining how logistics disruptions are handled. We are a team of mission-focused, world-class AI Engineers, mobility, and logistics experts (and some business folks) who are leveraging big data and cutting-edge technology to develop the next generation of technologies for addressing how our partners can better prepare for contested mobility disruptions. Together, we are building much needed solutions to address our Nation's pressing challenges in the areas of logistics and mobility. 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-equival