Senior Dotnet Developer

CornerStone Technology Talent Services is seeking an experienced Senior .NET Application Developer / Technical Lead for a hands-on software development opportunity supporting mission-critical applications within a public-sector law-enforcement technology environment.This role is designed for a seasoned application developer who can independently design, build, enhance, troubleshoot, test, and support enterprise web applications and APIs using Microsoft technologies.You will work alongside application developers, technical subject-matter experts, and business stakeholders to modernize and enhance existing systems, develop new functionality, improve database performance, build integrations, create operational reporting, and resolve complex application issues.This is not a project-management-only role. We are looking for someone who remains technically hands-on and can contribute directly to C#/.NET development, SQL Server, APIs, XML/JSON integrations, reporting, testing, debugging, and application support.What You'll DoIn this role, you will:Design, develop, enhance, and maintain custom enterprise web applications.Develop applications and services using C#, ASP.NET, .NET Core, and related Microsoft development technologies.Design and develop RESTful APIs and system integrations.Develop data-transport and integration solutions using XML and JSON.Troubleshoot, debug, and resolve complex application and production issues.Design, develop, and optimize SQL Server databases, queries, stored procedures, and application data solutions.Improve database and application performance through query optimization and technical analysis.Develop operational and business reporting using SSRS, Power BI, or comparable reporting technologies.Perform and support unit testing, integration testing, and application validation.Develop and maintain test cases and technical test scripts.Support and enhance both custom-built applications and commercial/modified-off-the-shelf systems (COTS/MOTS).Analyze existing applications and recommend enhancements based on technical requirements, user needs, and industry best practices.Collaborate with technical SMEs and stakeholders to identify application defects, system improvements, and business-process enhancements.Evaluate how proposed changes affect existing applications, integrations, databases, workflows, and business processes.Create and maintain technical specifications, system documentation, application-support documentation, test cases, and technical requirements.Provide ongoing production and application support while documenting issues, root causes, and resolutions.Contribute to application modernization, automation, and continuous improvement initiatives.Required Technical ExperienceTo be considered, you should bring:5+ years of professional web application development experience using .NET technologies or comparable enterprise web-development technologies.Strong hands-on development experience with C# and the Microsoft .NET ecosystem.Experience with technologies such as:ASP.NET.NET CoreBlazorRazorWeb APIsSimilar modern web-development frameworks3+ years of hands-on XML and/or JSON integration experience.5+ years of unit-testing and integration-testing experience.5+ years of SSRS and/or Power BI experience.5+ years supporting COTS and/or MOTS enterprise applications.5+ years of SQL database programming and architecture experience.Strong experience developing and optimizing:SQL databasesQueriesStored proceduresData-access solutionsApplication data modelsDatabase performanceExperience troubleshooting and debugging enterprise software applications.Experience creating technical specifications, test cases, and application documentation.Public Safety / Law Enforcement Experience – RequiredCandidates must have at least 5 years of professional IT experience supporting law-enforcement technology environments.Relevant backgrounds may include technology supporting:Law-enforcement agenciesPolice departmentsSheriff's officesCorrectionsProbation or paroleCriminal-justice systemsPublic-safety applicationsSimilar law-enforcement technology environmentsThis experience must be clearly demonstrated within your professional work history.General government experience without direct law-enforcement IT exposure will not satisfy this requirement.Preferred Technology ExperienceAdditional experience with any of the following will make you especially competitive:AI agents or AI-enabled development toolsMicrosoft 365 developmentSharePointPower AppsPower BIGitHubAzure DevOpsCI/CD practicesSource-control and release-management processesPowerShell scripting and automationAutomated test developmentTest-script creationApplication modernizationAPI integrationEnterprise workflow automationWhat We're Looking ForThe strongest candidates are developers who can move comfortably across the application stack rather than specializing in only one narrow area.You should be comfortable moving from:C#/.NET development ? API integration ? SQL troubleshooting ? reporting ? testing ? production support ? technical documentationwithout losing sight of the business problem the application is intended to solve.We're especially interested in professionals who:Can work effectively with limited supervision.Take ownership of technical problems through resolution.Can investigate unfamiliar applications and determine how they work.Understand the relationship between applications, databases, integrations, and business processes.Write clean, maintainable, testable code.Communicate technical issues clearly to both technical and nontechnical stakeholders.Document solutions rather than allowing knowledge to remain tribal.Balance new development with enhancement and production-support responsibilities.Can work effectively with application developers, business users, infrastructure teams, and technical SMEs.EducationCandidates should have a Bachelor's degree, advanced education in Computer Science, Information Systems, Technology Management, or a related discipline, or substantial equivalent professional experience.Location RequirementThis opportunity requires a hybrid schedule in Columbia, South Carolina, with approximately two days onsite each week.Candidates must be current South Carolina residents.Relocation candidates cannot be considered for this opportunity.Pre-Employment RequirementsCandidates selected for this public-sector environment should be prepared to complete comprehensive pre-employment screening, which may include:Criminal-background verificationDrug screeningEmployment verificationEducation verificationProfessional-reference checksIdentity and employment-eligibility verificationCredit/background screening as required for the environmentWhy Work with CornerStone Technology Talent Services?CornerStone Technology Talent Services connects experienced technology professionals with organizations tackling meaningful, complex IT initiatives.Our recruiting team works to understand both the technology and the person behind the resume. We provide:Direct communication throughout the recruiting processClear expectations about the opportunity before you move forwardTechnical recruiting support from professionals who understand the roles they're recruiting forAccess to contract, contract-to-hire, and direct-hire technology opportunitiesSupport throughout your assignment, not just through your first dayIf you're an experienced .NET/C# developer with deep SQL expertise and significant law-enforcement IT experience who enjoys solving complex application problems, we'd like to hear from you.