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You will get ASP.NET Core HIGH-PERFORMANCE RESILIENT REST API
Project details
I offer the development of a high-performance, production-ready ASP.NET Core REST API with a clean, modular architecture. My approach emphasizes scalability, resilience, and maintainability — ideal for enterprise or high-load systems.
The solution includes:
1. Clean Architecture & CQRS with MediatR for separation of concerns and testability
2. FluentValidation for robust and consistent input validation
3. Entity Framework Core for efficient data access and LINQ-based querying
4. Identity Framework for secure user authentication and role-based authorization
5. Polly for advanced resiliency features like retries, circuit breakers, and timeouts
6. Serilog for structured logging and observability
7. Swagger/OpenAPI support for interactive API documentation and client generation
8. Database support for SQL Server, PostgreSQL, MySQL, or others upon request
This project is ideal for businesses needing a modern, secure, and extensible backend API that can scale with demand and handle real-world failures gracefully.
The solution includes:
1. Clean Architecture & CQRS with MediatR for separation of concerns and testability
2. FluentValidation for robust and consistent input validation
3. Entity Framework Core for efficient data access and LINQ-based querying
4. Identity Framework for secure user authentication and role-based authorization
5. Polly for advanced resiliency features like retries, circuit breakers, and timeouts
6. Serilog for structured logging and observability
7. Swagger/OpenAPI support for interactive API documentation and client generation
8. Database support for SQL Server, PostgreSQL, MySQL, or others upon request
This project is ideal for businesses needing a modern, secure, and extensible backend API that can scale with demand and handle real-world failures gracefully.
Programming Languages
ASP.NET, TypeScript, C#Coding Expertise
Localization, Performance Optimization, SecurityWhat's included $269
These options are included with the project scope.
$269
- Delivery Time 10 days
- Number of Revisions 3
- Number of Pages 1
- Source Code
Optional add-ons
You can add these on the next page.
Deployment
(+ 1 Day)
+$69
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OS
Oleksii S.
Mar 18, 2026
C# Developer - Integration with Twilio SendGrid Email API
Sergey is an excellent .Net-expert. Communication was clear, deadlines were met, and he provided valuable recommendations beyond the initial scope. Highly reliable and professional (C#, ASP.NET Core, Web API, EF Core, SendGrid) — I would definitely hire him again!
OS
Oleksii S.
Feb 27, 2026
.Net Developer - Improve Azure Application Insights logging
Easy to work with Sergey - he is a real profesional (.NET Core, SOAP, MS Azure Cloud, Azure, Application Insights). Will work for next projects with Sergey again.
OS
Oleksii S.
Nov 22, 2025
C# Developer - Export the report to specific text format
Sergey was absolutely amazing really went the extra mile to deliver his best (C#, ASP.Net, .NET Core, Unit testing, JSON, SQL). Will work with hime again soon. Thank you!
OS
Oleksii S.
Nov 6, 2025
.Net - Developer - Add new catalogue to our application
Pleasure to work with Sergey. Quick communication and delivery of the project was ahead of schedule too (C#, .NET Framework, MS SQL Server, HTML, IIS, SVN, RDP, VPN, Visual Studio IDE). Highly recommended!
OS
Oleksii S.
Oct 30, 2025
.Net Developer - Integration with external service
Working with Sergey was excellent. He's a top-notch developer (C#, .NET Core, MS SQL Server, Background Service, HTTP, JSON). I'll definitely hire him for future projects without hesitation.
About Sergey
Senior Back-End Developer | C# | .Net | Web App Development
100%
Job Success
Zaporizhzhya, Ukraine - 8:45 pm local time
💡 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
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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
Steps for completing your project
After purchasing the project, send requirements so Sergey can start the project.
Delivery time starts when Sergey receives requirements from you.
Sergey works on your project following the steps below.
Revisions may occur after the delivery date.
Understand and confirm project scope
Review the provided specification, clarify goals, confirm tech stack, and align on success criteria before development begins.
Set up the project on the local environment
Clone the repo or initialize a new solution. Configure databases, authentication, and dependencies to match production for accurate development and testing.