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Sergey A.
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Sergey A.

Senior Back-End Developer | C# | .Net | Web App Development

🏆 .NET Developer with 20+ years of experience building scalable, high-performance web applications and backend systems. I specialize in ASP.NET Core, C#, MVC, Web API, and SQL Server to deliver robust, secure, and user-friendly solutions. 💡 Key Competencies: 🔹 Backend Development: C# | ASP.NET Core ⚡ Building scalable and secure backend systems with ASP.NET Core and C# ⚡ Developing RESTful APIs for seamless frontend-backend communication ⚡ Implementing authentication and authorization using JWT and OAuth ⚡ Middleware development for request handling and validation 🔹 Frontend Development: 📌 Creating dynamic, responsive, and interactive user interfaces with ASP.NET MVC and Razor Pages 📌 Integration with RESTful APIs and third-party libraries 📌 Responsive web design with CSS, Bootstrap, and JavaScript 📌 Building web applications with Angular, PrimeNG, TypeScript 📌 Blazor for building interactive web applications with C# 🔹 Database Management: SQL Server and PostgreSql 🌟 Designing and optimizing databases for performance and scalability 🌟 CRUD operations and complex query implementation 🌟 Data modeling and schema design for efficient data storage 🌟 Integration with Entity Framework Core, NHibernate and Dapper for streamlined database interactions 🔹 Microservices Architecture: 🌠 Using Docker for containerization and deployment 🔹 Fullstack Development: ⭐️ End-to-end development of web applications, from concept to deployment ⭐️ Seamless integration of frontend and backend systems ⭐️ Deployment on cloud platforms like Azure and AWS ⭐️ Version control with SVN, TFS, Git and collaborative workflows 🔹 Additional Skills: ✨ Testing with xUnit and Moq ✨ Agile methodologies for project management ✨ CI/CD pipelines for automated deployment ✨ Performance optimization for faster load times 💡 Why Choose Me? 🔥 Proven Expertise: Delivered 20+ .NET projects with measurable results 🔥 Scalable Solutions: Build applications that grow with your business 🔥 Client-Centric Approach: Clear communication, timely delivery, and dedicated support 🔥 Future-Proof Development: Write clean, maintainable, and well-documented code 🔥 Continuous Learning: Always updating my skills to stay ahead in the ever-evolving tech landscape 💡 Technical Stack: 📌 Backend: ASP.NET Core, C#, RESTful APIs, SignalR, Entity Framework Core 📌 Frontend: Angular, React, ASP.NET MVC, Blazor, CSS3, Bootstrap, JavaScript 📌 Database: SQL Server, PostgreSql, Entity Framework Core, other ORMs 📌 Tools: Git, Docker, xUnit, Moq 📌 Deployment: Azure 💡 Recent Projects: 🌎 Developed web system using ASP.NET Core Web API, Angular, PrimeNG, DevExtrem 🌎 Build different integrations using Azure Functions, Azure Storage, CosmosDB 🌎 Improve security with Azure Key Vault 🌎 Bug fix and implement new features for existed systems 🌎 Support and bug fix for big legacy distributed system .NET Developer Upwork .NET Development Upwork ASP.NET Developer Upwork ASP.NET Core Developer Upwork C# Developer Upwork .NET Web Development Upwork .NET Application Development Upwork .NET Software Developer Upwork .NET API Development Upwork .NET Backend Developer Upwork .NET Full Stack Developer Upwork ASP.NET MVC Developer Upwork .NET Core Developer Upwork .NET REST API Developer Upwork .NET Web API Development Upwork .NET Enterprise Application Development Upwork .NET Database Development Upwork .NET SQL Server Developer Upwork .NET Azure Developer Upwork .NET Cloud Application Development Upwork .NET Integration Developer Upwork .NET Performance Optimization Upwork .NET Maintenance and Support Upwork .NET Migration & Upgrade Services Upwork Skill Keywords# ASP.NET Developer | Blazor | Angular | ASP.NET Core MVC Developer | .NET Backend Engineer | Senior Full-Stack C# Developer | Clean Architecture in .NET | Freelance Enterprise .NET Developer | Microsoft Azure .NET Specialist | Cloud-Native .NET Engineer | .NET Dev with CI/CD Pipelines | Dockerized .NET App Developer | Finance & Insurance .NET Systems | API Development & Documentation (Swagger, Postman) | Backend Developer (.NET Core) | SQL Server Optimization & Query Tuning | Entity Framework Core + Code-First Dev | T-SQL / Stored Procedure | RESTful API Developer | Agile & Scrum-Based Project Experience | DevOps on Azure + GitHub Actions | Secure App Developer (JWT, Role-based Auth) | Localization & Globalization in .NET Apps | PDF & Excel Report Generator in .NET | Upwork Verified .NET Expert | ASP.NET Identity & Claims-Based Authorization | Automated Unit Testing with xUnit & NUnit | Azure App Service + Azure Storage + Key Vault Setup | Legacy App Modernization - .NET Framework to .NET Core

🇺🇦Zaporizhzhya, Ukraine$19/hr100% JSS5.00 (29)Since Apr 2014

Earnings and projects

MRR
$0

Last 6 months ÷ 6

World#283,590 / 412k
🇺🇦Country#11,165 / 14.3k
Revenue, last 30 days
$0
Total earnings
$3.6k

Billed in all: $3.8k

World#283,590 / 412k
🇺🇦Country#11,165 / 14.3k
Per project
$119
Projects, last 6 months
0

Across 1 contracts

0% fixed100% hourly
World#209,850 / 412k
🇺🇦Country#7,324 / 14.3k
Projects in all
30

Across 31 contracts

77% fixed23% hourly
World#97,486 / 412k
🇺🇦Country#4,267 / 14.3k

Earnings, last 30 days

$3.8kNothing earned in the last 30 daysBilled in all, before Upwork's fee · drag across the chart to see what was earned in any stretch
$3,700$3,750$3,800$3,850Oct 8Oct 23Nov 7

Skills