full stack developer for enterprise web applications

The client requires occasional on-site work at its premises in Warsaw, Poland, for enterprise-level web applications in a complex IT environment.

• Design, develop, and maintain enterprise web applications using C#, ASP.NET Core / .NET 8, Entity Framework, and SQL Server
• Develop responsive single-page applications using React and TypeScript
• Translate functional and business requirements into technical designs, using UML where appropriate
• Design and implement application components across data, business logic, and presentation layers
• Optimize application performance, security, reliability, and maintainability
• Contribute to software integration, prototyping, testing, and quality assurance
• Provide technical guidance to development teams and promote best practices and coding standards
• Participate in Agile/Scrum activities, technical planning, and effort estimation
• Conduct code reviews, identify technical debt, and propose improvements
• Produce and maintain technical documentation, solution designs, and development specifications
• Collaborate with external development partners on knowledge transfer, application handover, and technical continuity
• Manage application builds, deployments, and releases using Azure DevOps Pipelines
• Support application deployment and operations across Windows/IIS, virtualized, and containerized environments, including Nutanix or OpenShift
• Implement and maintain background-processing services using frameworks such as Hangfire
• Support application security mechanisms, including ASP.NET Core Data Protection, certificate management, and identity federation
• Address vulnerabilities identified through security scanning, including Checkmarx, and penetration testing
• Integrate enterprise applications with authentication and identity-management solutions, including SAML 2.0 and Microsoft Entra ID
• Develop and maintain integrations involving document-management systems, PDF generation, and image-processing technologies
• Provide second- and third-line application support, including incident investigation, troubleshooting, and root-cause analysis
• Support user acceptance testing (UAT), change management, and release coordination through governance processes, including Change Advisory Boards (CAB)
• Work with third-party contractors during application transition and support periods to ensure operational stability and continuity

• At least 8 years of experience in IT, including at least 6 years using the mentioned tools
• UML certification
• Certification in software development related to .NET/Microsoft technologies, such as Azure or C#
• Strong professional experience developing and supporting enterprise applications using C#, ASP.NET Core / .NET 8, and Entity Framework
• Front-end development experience with React and TypeScript
• Knowledge of SQL Server, database design, and application data management
• Hands-on experience with Azure DevOps, CI/CD pipelines, and application release processes
• Understanding of multi-tier application architecture, object-oriented design, and UML modelling
• Experience in Agile/Scrum environments
• Familiarity with application hosting and deployment on Windows/IIS and containerized or virtualized infrastructure
• Experience with enterprise authentication, application security, and secure development practices
• Ability to support production applications and resolve complex technical issues

• Contract employment