Senior .NET Developer / Lead Application Developer

American IT Systems•Lisle, IL

About The Position

We are seeking an experienced .NET developer to lead the design, development, enhancement, and modernization of business-critical applications. The candidate will work closely with business stakeholders, technical teams, and support teams to deliver scalable, secure, and maintainable solutions across web applications, backend services, APIs, databases, and integration platforms.

Requirements

10+ years of professional software development experience, preferably with significant hands-on experience in the Microsoft technology stack.
Strong experience with C#, .NET Framework, ASP.NET, ASP.NET Core, MVC, Web API, ADO.NET, Entity Framework, WCF, and related technologies.
Experience developing and supporting N-tier, client/server, web-based, and service-oriented applications.
Strong database development skills with SQL Server, including query optimization, stored procedures, triggers, and performance tuning.
Experience with front-end development using HTML5, CSS, Bootstrap, JavaScript, jQuery, Angular, React, JSON, and AJAX.
Working knowledge of object-oriented programming principles, SOLID principles, design patterns, and clean coding practices.
Experience with source control, DevOps, and delivery tools such as Azure DevOps, GitHub, TFS, Visual Studio, VS Code, Postman, and SoapUI.
Ability to create technical design documents, use cases, test cases, deployment documentation, and user-facing documentation.
Strong analytical, troubleshooting, communication, and stakeholder-management skills.

Responsibilities

Design, develop, test, deploy, and maintain enterprise applications using C#, ASP.NET, ASP.NET Core, MVC, Web API, and related Microsoft technologies.
Modernize legacy .NET applications and services to improve performance, reliability, maintainability, and user experience.
Build and consume RESTful APIs and web services to support integrations with internal and external systems.
Develop responsive user interfaces using HTML5, CSS, Bootstrap, JavaScript, jQuery, Angular, and React where applicable.
Create and optimize SQL queries, stored procedures, triggers, indexes, and database objects across SQL Server and other relational databases.
Participate in requirements gathering, analysis, technical design, solution estimation, documentation, testing, and implementation activities.
Support Agile delivery practices, including sprint planning, backlog refinement, code reviews, unit testing, and release coordination.
Provide production support, troubleshoot application issues, analyze root causes, and implement corrective actions.
Collaborate with business users, product owners, QA teams, infrastructure teams, and offshore/onshore development teams.
Contribute to CI/CD pipelines, source control practices, build automation, and deployment processes using tools such as Azure DevOps, GitHub, and TFS.