- Backend & Enterprise: C#, Java, SQL, ASP.NET Core, Spring Boot, REST, GraphQL, WebSocket, Swagger
- Distributed Systems & APIs: REST, GraphQL, WebSocket, OAuth2, JWT, API Gateways, Stripe, PayPal, Postman
- DevOps & Infrastructure: Docker, Kubernetes, GitHub Actions, CI/CD, Linux, Apache, Nginx, Bash, PowerShell
- Databases: PostgreSQL, MySQL, MSSQL, MongoDB — schema design, indexing, migrations, tuning
- Frontend (supporting): React, Blazor, Razor Pages, HTML/CSS, JavaScript, TypeScript, TailwindCSS
- Mobile Development: Android (Java/Kotlin), iOS (Swift/SwiftUI), MAUI, Flutter
- Testing & Tooling: xUnit, NUnit, JUnit, Moq, Cypress, Git, GitHub, JetBrains, VS Code, Vim
- System & Security: Server administration, SSH, IAM, Encryption, Secure coding, GDPR, DevSecOps