Senior / Lead .NET Developer

American IT Systems; Lisle (IL); On-site; USD 120,000 - 160,000; Full time

Job summary

American IT Systems seeks a senior software engineer to design, build, and modernize enterprise applications using C#, .NET, ASP.NET, MVC, and related Microsoft tech in a fast-paced environment.

You will develop RESTful APIs, build responsive UIs with Angular/React, and optimize SQL Server databases while participating in requirements, design, and delivery processes. Strong DevOps and collaboration are essential.

Qualifications

• 10+ years of professional software development experience in Microsoft stack.
• Strong experience with C#, .NET Framework, ASP.NET, ASP.NET Core, MVC, Web API.
• Experience with N-tier, client/server, and service-oriented apps.
• Deep SQL Server knowledge: queries, stored procedures, tuning.
• Frontend experience: HTML5/CSS/JS, Angular/React, JSON, AJAX.
• Solid OO, SOLID, design patterns, clean coding practices.
• Familiar with DevOps, Azure DevOps, GitHub, TFS, and code reviews.
• Able to produce technical docs, use cases, tests, and deployment guides.
• Strong analytical and stakeholder management skills.

Responsibilities

• Design, develop, test, deploy, and maintain enterprise apps with Microsoft tech.
• Modernize legacy .NET applications to boost performance and UX.
• Build and consume RESTful APIs for internal/external integrations.
• Develop responsive UIs using HTML5, CSS, Bootstrap, JS, Angular/React.
• Create/optimize SQL objects across SQL Server and related DBs.
• Participate in requirements, design, estimation, docs, testing, implementation.
• Support Agile practices: sprint planning, reviews, backlogs, CI/CD coordination.
• Provide production support, troubleshoot, root-cause analysis, fixes.
• Collaborate with business users, product owners, QA, infra, offshore/onshore teams.
• Contribute to CI/CD pipelines and deployment processes using Azure DevOps, GitHub, TFS.

Skills

C#

ASP.NET

ASP.NET Core

MVC

Entity Framework

SQL Server

RESTful APIs

JavaScript

Angular/React

OO Principles

Education

Bachelor's degree in CS/IT/Engineering

Advanced degree or related certs

Tools

Azure DevOps

GitHub

TFS

Visual Studio

VS Code

Postman

SoapUI

SSMS

Job description

Key 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.

Required Qualifications

• 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.

Preferred Qualifications

• Experience leading small development teams or coordinating work between onshore and offshore teams.
• Experience with application modernization, legacy system remediation, technical debt reduction, and platform upgrades.
• Experience integrating third-party services, AI-enabled services, transcript/document processing, or business workflow automation.
• Experience in manufacturing, automotive, legal technology, industrial, or enterprise business systems environments.
• Familiarity with Oracle, DB2, LiteDB, PostgreSQL, SharePoint, IIS, Windows Server, and cloud-oriented delivery practices.

Education and Certifications

• Bachelor's degree in Computer Science, Information Technology, Engineering, or a related field preferred; equivalent professional experience may be considered.
• Advanced degree or formal computer applications education is a plus.
• Relevant Microsoft, .NET, cloud, DevOps, database, or application development certifications are preferred.

Technical Skill Areas

Category

Representative Skills

Languages and Frameworks

C#, VB.NET, ASP.NET, ASP.NET Core, MVC, .NET Framework, LINQ, Entity Framework

APIs and Services

REST, SOAP, Web API, WCF, backend services, third-party integrations

Front-End

HTML5, CSS, Bootstrap, JavaScript, jQuery, Angular, React, AJAX, JSON

Databases

SQL Server, Oracle, DB2, PostgreSQL, LiteDB, stored procedures, triggers, query optimization

DevOps and Tools

Azure DevOps, GitHub, TFS, Visual Studio, VS Code, Postman, SoapUI, SSMS

Delivery Practices

Agile, Waterfall, CI/CD, code reviews, testing, production support, technical documentation