Languages & Platforms:
• C# (.NET 6–8, .NET Framework 4.5–4.7)
• Backend development: monoliths and microservices
• Desktop applications: WPF (MVVM)
• Web applications: ASP.NET MVC
• Rest API, WebSockets, gRPC, TCP Sockets
• HTML, CSS, JS
• PowerShell, VBS
Architecture & Principles:
• SOLID, KISS, DDD
• Layered architecture
• Dependency Injection (DI)
• GoF Patterns
• Refactoring Legacy codebase
Databases & ORM:
• PostgreSQL, MSSQL
• Schema design
• Indexes
• Entity Framework (Database First and Code First expirience)
Multithreading:
• Threads, Tasks, async/await
• Synchronization primitives
• Concurrent collections
• Interlocked
Infrastructure:
• GitLab CI/CD pipelines
• Docker
• Kubernetes (application-level usage)
• ArgoCD
Networking:
• OSI model, TCP/IP fundamentals
• Network troubleshooting
• System administration background

Additional Expertise (System Administration)
• OS: Windows Server 2000–2019, Ubuntu, Debian, FreeBSD
• Services: DNS, DHCP, DFS, WSUS, WDS, ISCSI, Failover Clustering
• Active Directory (GPO, Sites, geographically distributed infrastructure)
• Virtualization: Hyper-V Cluster, Live Migration, System Center
• Web Servers: IIS, Apache (Windows/Linux, LAMP)
• Automation: PowerShell, VBScript
• Databases: MSSQL (AlwaysOn cluster, backup/restore, replication), MySQL
• Mail Servers: Exchange, MDaemon, Kerio Mail
• Networking: MikroTik, Kerio, D-Link, VPN (PPTP, L2TP, IPSec)
• Monitoring: Zabbix, custom monitoring system
• Hardware: HP, Dell, HP C7000, HP 3PAR, Infotrend, RAID