Senior .NET Developer / Fullstack DeveloperLocation: Onsite, Hybrid - 3x days / week - Washington, DC
Clearance Required: Active Secret
Improvix Technologies is seeking a Senior .NET Developer to provide technical leadership and architectural direction for a fast-paced federal program delivering high-visibility mission outcomes. This role is ideal for a seasoned engineer who has grown beyond writing code into shaping how it gets written - someone who can evaluate competing technologies, define standards, and guide a team of developers toward sound, scalable solutions.
You will serve as the senior technical voice on the team, owning architecture and tooling decisions across a portfolio of Microsoft and modern web applications while mentoring developers and ensuring delivery quality across the full stack.
What You'll Do- Support the technical architecture for full stack applications built on .NET (C#/ASP.NET Core), React.js and other modern web frameworks, defining patterns, standards, and best practices for the development team
- Design, build, and maintain highly interactive, responsive web applications using React.js, ASP.NET Core and Azure Cloud Services.
- Develop test frameworks: Design, implement, and maintain scalable, reusable automated test frameworks from scratch for web UIs and front-end components to support test automation efforts.
- Evaluate, select, and recommend tools, frameworks, libraries, and platforms - weighing tradeoffs in scalability, maintainability, security, and total cost of ownership
- Actively participate in technical design reviews, establish coding standards, and oversee code review processes to ensure quality and consistency across the team
- Define and maintain technical roadmaps for application modernization, including migration of legacy SharePoint-backed systems to modern architectures
- Support architectural oversight for Microsoft Power Platform solutions - guiding when Power Apps (canvas and model-driven), Power Automate, and Dataverse are the right fit versus custom development
- Support establishing data architecture and governance patterns for Microsoft Dataverse, including table design, relationships, business rules, and security role models
- Guide API strategy and integration architecture, including RESTful service design, authentication patterns, and integration with Microsoft 365, SharePoint, Teams, and external systems
- Mentor mid-level and junior developers, conducting knowledge transfer sessions and growing the technical capability of the team
- Partner with program leadership, government stakeholders, and technical leads to translate mission requirements into achievable technical solutions
- Help improve CI/CD pipelines, branching strategies, and release management practices to support frequent, reliable deployments
- Identify and remediate technical debt, performance bottlenecks, and security risks across the application portfolio
- Remain hands-on as needed - prototyping solutions, unblocking developers, and contributing code to critical-path items
- Work onsite with the team to support rapid collaboration and delivery
What You BringRequired Qualifications- 5+ years of progressive experience in .NET development (C#, ASP.NET MVC, ASP.NET Core), React.js, xUnit, Playwright, Cypress or Selenium.
- Hands-on experience with agentic development life cycle to leverage AI Tools to expediate end to end development.
- Hands-on experience with Cloud services supports web application deployment and management.
- Demonstrated experience supporting architecture and technology selection decisions for enterprise applications - and the ability to articulate the reasoning behind them
- Strong command of full stack architecture, including modern frontend frameworks (React or similar), RESTful API design, and service-oriented patterns
- Hands-on experience with Microsoft Power Platform - including Power Apps (canvas and/or model-driven), Power Automate, and Power BI - with the judgment to know when low-code is and isn't the right answer
- Experience leading SharePoint modernization or migration efforts, with familiarity across SharePoint Online and legacy SharePoint (2013 or newer)
- Deep experience with MS SQL, Entity Framework, and database design for enterprise applications
- Proven experience establishing or maturing CI/CD pipelines and DevOps practices (GitHub Actions, Azure DevOps, or similar)
- Experience participating in code reviews, setting coding standards, and mentoring development teams
- Strong understanding of application security concepts, Active Directory, and identity/access patterns in enterprise environments
- Familiarity with Microsoft 365 / Office suite - including SharePoint Online, Teams, Outlook, Excel, Word, and OneDrive - in a collaborative enterprise environment
- Excellent communication skills, with the ability to present technical recommendations to both engineering teams and non-technical stakeholders
- Ability to work onsite in a federal environment (occasional Saturday hours may be required for deployment activities)
Preferred Qualifications- Experience architecting solutions in Azure cloud environments, including deployments in a federal or FedRAMP context
- Familiarity with Dataverse for Teams and Power Apps embedded in Microsoft Teams
- Experience with TypeScript across frontend and/or Node.js development
- Exposure to containerization and orchestration tools such as Docker or Kubernetes
- Experience integrating AI/LLM capabilities or AI-assisted developer tooling into team workflows
- Understanding of Section 508 accessibility standards
- Prior experience supporting federal government programs and working within government security and compliance frameworks
- Relevant certifications such as Microsoft Certified: Azure Solutions Architect, Power Platform Solution Architect, or equivalent
At Improvix, you'll join a collaborative, mission-focused environment where your expertise drives meaningful impact.
