You will get your existing .NET web application maintained and improved
Rising Talent
Project details
Do you have an existing C#/.NET application that needs bug fixes, maintenance, new functionality, or backend improvements?
I can help you understand, maintain, and extend your existing .NET codebase without unnecessary rewrites or architectural changes.
I have 5 years of professional .NET development experience working with enterprise applications using C#, ASP.NET Core, Entity Framework Core, SQL Server, PostgreSQL, REST APIs, Microservices, DDD, and Clean Architecture.
I can help with:
• Existing ASP.NET Core applications
• Backend bug fixes
• New REST API endpoints
• Business logic changes
• Entity Framework Core
• SQL Server and PostgreSQL
• Authentication and authorization
• Validation
• API integrations
• Background jobs
• Refactoring
• Performance improvements
• Legacy .NET code
• Application maintenance
When joining an existing project, I first understand the current architecture and execution flow before making changes.
My priority is to preserve existing behavior, follow the project's conventions, and implement focused, maintainable improvements.
Please contact me before ordering if the requested change affects several modules or if the scope is unclear.
I can help you understand, maintain, and extend your existing .NET codebase without unnecessary rewrites or architectural changes.
I have 5 years of professional .NET development experience working with enterprise applications using C#, ASP.NET Core, Entity Framework Core, SQL Server, PostgreSQL, REST APIs, Microservices, DDD, and Clean Architecture.
I can help with:
• Existing ASP.NET Core applications
• Backend bug fixes
• New REST API endpoints
• Business logic changes
• Entity Framework Core
• SQL Server and PostgreSQL
• Authentication and authorization
• Validation
• API integrations
• Background jobs
• Refactoring
• Performance improvements
• Legacy .NET code
• Application maintenance
When joining an existing project, I first understand the current architecture and execution flow before making changes.
My priority is to preserve existing behavior, follow the project's conventions, and implement focused, maintainable improvements.
Please contact me before ordering if the requested change affects several modules or if the scope is unclear.
Programming Languages
JavaScript, ASP.NET, C#Coding Expertise
Performance Optimization, SecurityWhat's included
| Service Tiers |
Starter
$30
|
Standard
$100
|
Advanced
$230
|
|---|---|---|---|
| Delivery Time | 1 day | 3 days | 5 days |
Number of Revisions | 1 | 2 | 2 |
Design Customization | - | ||
Content Upload | - | - | - |
Responsive Design | - | - | |
Source Code |
Optional add-ons
You can add these on the next page.
Additional Revision
+$15Frequently asked questions
About Phu
C# / ASP.NET Core Backend Developer | REST API | EF Core | Bug Fixing
Hanoi, Vietnam - 11:59 pm local time
I help clients build, maintain, troubleshoot, and improve .NET applications, especially when they need someone who can quickly understand an existing codebase and solve problems without introducing unnecessary complexity.
What I can help you with:
- Build REST APIs using ASP.NET Core
- Debug and fix existing C#/.NET applications
- Fix Entity Framework Core and database issues
- Design and optimize SQL Server/PostgreSQL queries
- Implement authentication and authorization with JWT
- Develop business logic and backend services
- Maintain and extend existing .NET codebases
- Refactor legacy or complex backend code
- Design database models and relationships
- Integrate third-party APIs and services
- Implement background jobs and scheduled processing
- Work with Microservices and distributed systems
- Dockerize and deploy .NET applications
Technologies I work with:
Backend
C#, .NET Core, .NET 8, .NET 9, ASP.NET Core, REST API, ABP Framework, Entity Framework Core, Dapper
Architecture
Clean Architecture, DDD, SOLID, Microservices, Repository Pattern, Dependency Injection
Database
SQL Server, PostgreSQL, Redis
Integration & Messaging
RabbitMQ, REST API, gRPC, Firebase Cloud Messaging
Background Processing & Workflow
Hangfire, Elsa Workflow, Camunda
Development Tools
Git, GitHub, GitLab, Swagger, Postman, Serilog
DevOps
Docker, Docker Compose, Linux, GitLab CI/CD, GitHub Actions, Jenkins, AWS EC2, AWS S3
I have worked on enterprise systems including investment portfolio management, business planning and approval systems, HR applications, e-invoice systems, reporting systems, and data-processing applications.
I’m comfortable joining an existing project, understanding its architecture, investigating issues independently, identifying root causes, and implementing focused solutions.
I’m currently building my reputation on Upwork, but I bring 5 years of professional .NET development experience. My goal is to build long-term trust here through reliable communication, clean implementation, and high-quality work.
If you have a C#/.NET backend issue, an API that needs fixing, or an existing application that needs maintenance or new functionality, feel free to contact me.
Steps for completing your project
After purchasing the project, send requirements so Phu can start the project.
Delivery time starts when Phu receives requirements from you.
Phu works on your project following the steps below.
Revisions may occur after the delivery date.
Understand the codebase
I will review the existing project structure, architecture, relevant modules, dependencies, and requested changes.
Analyze the impact
I will identify the components affected by the requested change and determine the safest implementation approach.