Senior Full-Stack Engineer (.NET / React) — Backend-Focused
First seen by Alion on Oct 8, 2026.
About the Role
We are looking for a highly experienced Senior Full-Stack Engineer with a strong focus on .NET backend development and system architecture. This is a backend-oriented position, with approximately 70–80% of the work focused on backend engineering and 20–30% on frontend development. You will work on complex production systems, take ownership of architectural decisions, and contribute to frontend development when needed. The ideal candidate has extensive hands-on experience with C#/.NET, a solid understanding of distributed systems, and practical frontend development experience, preferably with React. Experience with TypeScript would be a significant advantage.
Responsibilities
Take ownership of architectural decisions across backend services, including service boundaries, data ownership, idempotency, outbox patterns, caching, and failure handling.
Document important technical decisions and revisit them as requirements and system constraints evolve.
Design and evolve financially sensitive functionality, including double-entry wallet accounting, payments and withdrawals, inventory settlement, and auditable outcome-generation mechanisms.
Work across layers when necessary, from database schemas and Drizzle migrations through domain logic, Fastify APIs, asynchronous consumers, and React interfaces.
Provide technical leadership for the internal operations platform supporting catalog, fulfillment, finance, and customer-support workflows.
Establish engineering standards around contract-first APIs, deterministic testing, database migrations, and code-review quality.
Mentor other engineers while maintaining a hands-on individual-contributor role.
Own production reliability through observability, incident response, capacity planning, performance analysis, and ongoing reliability improvements.
Requirements
8+ years of professional software development experience.
Strong hands-on experience with C# and .NET backend development.
Experience designing and maintaining complex production backend systems.
Strong understanding of microservices, distributed architecture, asynchronous processing, and message brokers.
Experience with relational databases, transaction handling, and performance optimization.
Practical frontend development experience, preferably with React.
Ability to own technical decisions and work independently across the development lifecycle.
Strong Advantages
Hands-on experience with TypeScript.
Experience with RabbitMQ, Kafka, or similar messaging technologies.
Experience with high-load, transaction-heavy, or financial systems.
Experience with AWS, Docker, Kubernetes, and CI/CD pipelines.
About the Company
The company is a lean product team developing a consumer commerce platform that combines real-time 3D interactions with the purchase of physical products. The product also includes a real-money wallet and operational workflows for order processing and fulfillment. Their technology stack is built entirely around TypeScript. The engineering team is small and experienced, with engineers working closely with and reporting directly to the CTO, allowing for fast communication and decision-making.