Senior Full Stack Software Engineer

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, with a knack for rapidly integrating new technologies and methodologies.
• Agile Methodology Experience: An understanding and hands-on experience with agile development methodologies and version control tools.
• Agility in Tech: Demonstrated adaptability in the fast-paced tech landscape, continually embracing and integrating new technologies and methodologies.
• Education: While formal education in Computer Science or related fields is a plus, DefconAI values hands-on experience and demonstrable