Senior Full Stack .NET Developer / Principal Backend Engineer

Senior Full Stack .NET Developer / Principal Backend Engineer

Location: Seattle, WA

Position Type: Full-Time hybrid $180-200k+ + benefits

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

Competitive salary ($180-200+k) and performance-based bonus opportunities

Comprehensive health, dental, and vision coverage

Retirement plan options

Generous paid time off and holiday schedule

Professional development and continuing education support

Flexible work arrangements where applicable