Senior Full Stack .NET Developer / Principal Backend Engineer

Job Description
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 maintainbackend 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 workextensively 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 authenticationflows such as OAuth2 and OpenIddict , including support forserver-to-server interactions.
• Collaborate closely withfront-end engineers to ensure seamless React/TypeScript integration.

Architecture & Technical Leadership

• Drive the architectural directionacross products, ensuring scalability, reliability, and maintainability.
• Set and uphold high standards forengineering hygiene, code quality, and design practices.
• Mentor senior and juniorengineers, providing guidance in system design, coding practices, andproblem-solving.
• Translate complex technicaltopics into clear communication for both technical and non-technicalstakeholders.
• Identify, advocate for, and drive"delighter" features and improvements that enhance customer value.

Cloud, DevOps & Infrastructure

• Lead the design and operation oflarge-scale cloud services using AWS (EC2 and related services) orother major public cloud platforms.
• Apply DevOps and security bestpractices across development and deployment workflows.
• Utilize containerization andorchestration technologies such as Docker and Kubernetes .
• Contribute to evolvinginfrastructure that supports data workflows and emerging AI-relatedsystems.

Cross-Functional Collaboration

• Partner with product, data, andengineering teams to shape technical strategies and deliver high-impactinitiatives.
• Understand user needs andcustomer workflows to inform system improvements and product direction.
• Operate effectively in afast-paced environment with high ambiguity, balancing technical andbusiness priorities.

Requirements

Required Qualifications

• Bachelor's degree in ComputerScience or a related field.
• 12+ years of experience buildingand 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, andperformance optimization
• REST API design
• Dapper ORM
• OAuth2, OpenIddict, and modernauthentication patterns
• Demonstrated experience with atleast one major cloud provider (AWS, Azure, or GCP).
• Proficiency in at least oneadditional programming language (Java, TypeScript/JavaScript, Golang,Python, etc.).
• Experience with Docker , Kubernetes ,or other container orchestration systems.
• Ability to work directly with endusers or customers to understand requirements and user journeys.
• Strong communication skills withthe ability to clearly articulate technical decisions and trade-offs.
• Proven track record of developingtechnical strategies and executing them successfully.
• Ability to raise the engineeringbar for quality, reliability, security, and maintainability.
• Demonstrated successcollaborating across teams and driving complex cross-functionalinitiatives.

Nice-to-Have Qualifications

• Strong front-end experience with React and modern TypeScript frameworks.
• Experience supporting orarchitecting infrastructure for AI pipelines .
• Familiarity with NoSQLtechnologies, message queues, or event-driven architectures.
• Experience with WPF modernizationor transition to web-based UI frameworks.

Benefits

Benefits

• Competitive salary ($180-200+k) andperformance-based bonus opportunities
• Comprehensive health, dental, andvision coverage
• Retirement plan options
• Generous paid time off andholiday schedule
• Professional development andcontinuing education support
• Flexible work arrangements whereapplicable