Senior .NET Application Developer

Cynet Systems•Lisle, IL

About The Position

The Senior .NET Application Developer will support and enhance enterprise console and web applications. The role includes application maintenance, technical enhancements, production support, release management, application hosting, certificate management, database support, and customer collaboration. The developer works with technical leads and managers, developers, L1 support teams, Customer Support Managers, infrastructure and business operations teams, and customer stakeholders. The role requires strong troubleshooting skills, ownership, and the ability to independently manage assigned application support and enhancement activities. The position maintains, troubleshoots, and enhances applications using React, C#, VB.NET, ASP.NET MVC, .NET Core, Web APIs, and SQL Server, with occasional support for an Angular application. It involves deployment across Development, QA, and Production environments; code-level debugging and root-cause analysis; IIS and Windows Server hosting; Azure DevOps work; certificate and SSO configuration; SQL Server deployment support; production releases and incident response; and ad hoc reporting. On-call and after-hours production support may be required.

Requirements

Bachelor's degree in Computer Science, Information Technology, or a related field, or equivalent professional experience.
5–8 years of experience in software development, application maintenance, and production support.
Strong hands-on experience with React, C#, VB.NET, ASP.NET MVC, .NET Core, Web APIs, and SQL Server.
Ability to independently set up, configure, deploy, and troubleshoot React, ASP.NET MVC, .NET Core, and Web API applications.
Demonstrated experience with code-level debugging, root-cause analysis, and resolution of complex application issues.
Experience developing, analyzing, troubleshooting, and fine-tuning SQL queries and stored procedures.
Experience testing and troubleshooting REST APIs using Postman.
Working knowledge of JSON and XML, including parsing, integration, and troubleshooting.
Experience with Azure DevOps repositories, pull requests, work items, pipelines, and deployments.
Experience hosting and supporting web applications on IIS and Windows Server.
Experience with SQL Server deployments, troubleshooting, validation, and rollback activities.
Experience supporting production applications and participating in on-call support.
Experience with release management, change tickets, and production deployments.
Strong debugging, problem-solving, communication, and customer-interaction skills.
Ability to work independently and collaborate effectively with technical leads, developers, L1 support teams, CSMs, infrastructure teams, and customer stakeholders.
Must-have skills list states 8+ years of .NET development experience, 3+ years of React experience, and 4+ years of application support experience.

Nice To Haves

Experience supporting or troubleshooting Angular applications.
Familiarity with approved AI-assisted development tools such as GitHub Copilot.
Experience creating, configuring, and maintaining Azure DevOps CI/CD build and release pipelines.
Experience managing Microsoft Azure application configurations and deployments through CI/CD pipelines.
Experience querying and troubleshooting data in Db2 and Hadoop-based environments.
Experience with SolarWinds, ServiceNow, X-Matters, monitoring, and log-analysis tools.
Knowledge of Agile, Scrum, and ITIL practices.

Responsibilities

Maintain, troubleshoot, and enhance applications using React, C#, VB.NET, ASP.NET MVC, .NET Core, Web APIs, and SQL Server, with occasional support for an Angular-based application.
Set up, configure, deploy, and troubleshoot React, ASP.NET MVC, .NET Core, and Web API applications across Development, QA, and Production environments.
Support configuration and troubleshooting of the existing Angular application as required.
Perform code-level debugging and root-cause analysis for application, API, database, configuration, IIS, and deployment issues, and implement fixes.
Implement application fixes, technical improvements, performance enhancements, integrations, and customer-requested changes.
Collaborate with customers to understand requirements, investigate issues, recommend solutions, and provide technical updates.
Work with technical leads and developers on application maintenance, enhancements, code reviews, and production support.
Review Azure DevOps pull requests and perform code merges, tagging, builds, and deployments.
Create and manage Azure DevOps user stories, tasks, bugs, and support work items.
Perform releases across Development, QA, and Production environments.
Configure IIS, host web applications, and manage application pools, bindings, certificates, and server configurations.
Set up batch jobs and manage configuration changes across application environments.
Renew and install SSL/TLS and server certificates, and support SSO-related configurations in Azure and Windows Server environments.
Prepare database deployment, validation, and rollback scripts, and coordinate database backups as required.
Analyze, troubleshoot, and fine-tune SQL queries and stored procedures.
Create production change tickets and participate in release meetings, deployments, validation, and post-release monitoring.
Participate in high-severity incident calls and assist with troubleshooting, mitigation, and service restoration.
Analyze application, server, database, and batch-job logs.
Provide on-call and after-hours production support when required.
Create ad hoc reports based on customer and business requirements.