Senior Full Stack Engineer - .Net/React.js
First seen by Alion on Nov 14, 2026.
Experience: 8+ years.
Required Skills: C#, .NET, React/Next.js, PostgreSQL, AWS, REST APIs, SQL Server.
Job Summary:
We are looking for an experienced Senior Full Stack .NET Engineer to design, develop, and maintain scalable applications for a flagship loan origination, decisioning, and servicing platform. The ideal candidate will have strong expertise in C#/.NET, React-based front-end development, database technologies, and AWS cloud infrastructure, with end-to-end ownership of feature delivery and third-party integrations.
Key Responsibilities:
- Design, develop, and maintain full-stack applications using Next.js, React, C#/.NET, PostgreSQL, and AWS.
- Build scalable, secure, and high-performance RESTful APIs and backend services.
- Integrate third-party systems, including credit bureaus, dealer platforms, fraud detection, and identity verification providers.
- Configure and extend the DEFI Solutions Loan Origination System (LOS), including workflows, business rules, scorecards, and decision flows.
- Develop integrations with DEFI using REST APIs and Microsoft SQL Server.
- Deploy and manage containerized applications using AWS ECS/EKS, Fargate, and Docker.
- Collaborate with Product, Design, and Business teams to deliver features from requirements through production deployment.
- Ensure code quality, automated testing, performance, security, observability, and system reliability.
- Participate in code reviews, technical design discussions, and mentoring of team members.
- Leverage AI-assisted development tools such as GitHub Copilot, Cursor, and Claude Code to improve engineering productivity.
Required Skills & Qualifications:
- 7+ years of professional software development experience.
- Strong hands-on expertise in C#, .NET/.NET Core, and modern full-stack application development.
- Experience with React and Next.js for front-end development.
- Strong knowledge of PostgreSQL or other relational databases, SQL Server, and T-SQL.
- Experience designing and integrating RESTful APIs.
- Hands-on experience with AWS cloud services, containerization, and Docker.
- Knowledge of CI/CD pipelines, automated testing, application security, and performance optimization.
- Bachelor's degree in Computer Science, Engineering, or a related field, or equivalent practical experience.
Preferred Qualifications:
- Experience with DEFI Solutions or other Loan Origination Systems (LOS).
- Domain experience in auto finance, lending, banking, or other regulated industries.
- Knowledge of event-driven architecture and messaging services such as AWS SNS, SQS, EventBridge, or Kafka.
- Experience integrating machine learning-based scoring, decisioning, or underwriting models into production applications.
- Experience with AI-assisted coding and development tools.
Must-Have Skills for Screening:
- C#/.NET + React/Next.js + AWS + REST APIs + SQL/PostgreSQL.
Good to Have:
- DEFI Solutions / Loan Origination Systems, lending or auto-finance domain, Kafka or AWS messaging services.
Skills
Full Stack, C#, .Net, React.js, Next.js, AWS, PostgreSQL, SQL Server, RESTful API