Senior Full Stack .NET Developer / Principal Backend Engineer

Senior Full Stack .NET Developer / Principal Backend Engineer

Location: Seattle, WA

Position Type: Full\-Time hybrid

Overview

This role serves as a senior technical leader responsible for driving backend architecture, guiding engineering best practices, and contributing across the full technology stack. The position focuses heavily on backend systems built with C# and .NET, while also supporting front\-end integration efforts when needed. The engineer in this role will help shape the architectural vision, elevate engineering quality, and provide technical mentorship to the broader team.

Key Responsibilities

Backend & Full\-Stack Development

• Design, develop, and maintain backend applications using C#, .NET Framework, .NET Core, and .NET 8.
  


• Build and optimize REST APIs, including API versioning and BFF (Backend\-for\-Frontend) patterns.
  


• Lead data modeling and work extensively with SQL Server, including stored procedures, performance tuning, and Dapper (repository/unit\-of\-work patterns).
  


• Modernize or translate existing WPF components where needed.
  


• Implement secure authentication flows such as OAuth2 and OpenIddict, including support for server\-to\-server interactions.
  


• Collaborate closely with front\-end engineers to ensure seamless React/TypeScript integration.
  

Architecture & Technical Leadership

• Drive the architectural direction across products, ensuring scalability, reliability, and maintainability.
  


• Set and uphold high standards for engineering hygiene, code quality, and design practices.
  


• Mentor senior and junior engineers, providing guidance in system design, coding practices, and problem\-solving.
  


• Translate complex technical topics into clear communication for both technical and non\-technical stakeholders.
  


• Identify, advocate for, and drive “delighter” features and improvements that enhance customer value.
  

Cloud, DevOps & Infrastructure

• Lead the design and operation of large\-scale cloud services using AWS (EC2 and related services) or other major public cloud platforms.
  


• Apply DevOps and security best practices across development and deployment workflows.
  


• Utilize containerization and orchestration technologies such as Docker and Kubernetes.
  


• Contribute to evolving infrastructure that supports data workflows and emerging AI\-related systems.
  

Cross\-Functional Collaboration

• Partner with product, data, and engineering teams to shape technical strategies and deliver high\-impact initiatives.
  


• Understand user needs and customer workflows to inform system improvements and product direction.
  


• Operate effectively in a fast\-paced environment with high ambiguity, balancing technical and business priorities.
  

Requirements

Required Qualifications

• Bachelor’s degree in Computer Science or a related field.
  


• 12+ years of experience building and operating large\-scale cloud services or distributed systems.
  


• Expert\-level proficiency in C# and the .NET ecosystem (.NET Framework, .NET Core, .NET 8).
  


• Strong experience with:
  




• SQL Server, relational databases, and performance optimization
  


• REST API design
  


• Dapper ORM
  


• OAuth2, OpenIddict, and modern authentication patterns
  




• Demonstrated experience with at least one major cloud provider (AWS, Azure, or GCP).
  


• Proficiency in at least one additional programming language (Java, TypeScript/JavaScript, Golang, Python, etc.).
  


• Experience with Docker, Kubernetes, or other container orchestration systems.
  


• Ability to work directly with end users or customers to understand requirements and user journeys.
  


• Strong communication skills with the ability to clearly articulate technical decisions and trade\-offs.
  


• Proven track record of developing technical strategies and executing them successfully.
  


• Ability to raise the engineering bar for quality, reliability, security, and maintainability.
  


• Demonstrated success collaborating across teams and driving complex cross\-functional initiatives.
  

Nice\-to\-Have Qualifications

• Strong front\-end experience with React and modern TypeScript frameworks.
  


• Experience supporting or architecting infrastructure for AI pipelines.
  


• Familiarity with NoSQL technologies, message queues, or event\-driven architectures.
  


• Experience with WPF modernization or transition to web\-based UI frameworks.
  

Benefits