Hi, I'm Dang Vinh Hien
Mid-Senior Fullstack Developer
I am a Fullstack Developer specializing in POS system development with over 5 years of experience in .NET (C#, .NET Core, Web API) and SQL Server optimization.
Work Experience
NhatViet Solution
Developer
Developed and optimized Android and WinForm applications using Android Studio and .NET Framework.
Designed and implemented the company website using Node.js.
Collaborated in a small team (4 devs, 2 testers) to deliver production-ready solutions for internal systems.
Enrich Management System
Fullstack Developer / Team Support
Developed and optimized POS systems using .NET Core and MSSQL.
Designed and implemented API Gateway with Ocelot on IIS/Nginx environments.
Optimized SQL queries to improve data processing speed for large datasets.
Utilized Docker for deployment and development environment management.
Integrated third-party APIs: Authorize.Net (online payment), Twilio & SendGrid (SMS/Email).
Supported team code review, branching strategy, and technical solutions to enhance scalability and security.
Featured Projects
POS System for Nail Salons
Enterprise POS system for nail salons in the US. Features include employee & customer management, gift cards, loyalty, booking, online payments, and reporting.
POS Real-time Socket Service
Real-time communication system built with ASP.NET Core SignalR, Docker, and Nginx to synchronize user devices in POS environment.
POS Interface Middleware
WinForms middleware application enabling printers and payment devices (Pax, Clover) to connect with POS web systems via WebSocket.
Technical Skills
Backend Expertise
MSSQL optimization: execution plan, indexing, partitioning, query tuning
Real-time communication with SignalR & Socket.IO
Background jobs & queue processing with Hangfire
SQL Expertise
Experienced in complex query optimization (improved from 20s → 0.2s)
Skilled in database design, normalization, and indexing strategy
Strong understanding of execution plans and performance tuning
Familiar with data backup, replication, and high-availability setup
System & Deployment
Load balancing with Nginx
Containerization with Docker
CI/CD with GitHub Actions
Caching with Redis
System performance tuning and scaling
AI-assisted Development
Applying AI to support coding and documentation
Automating repetitive tasks to improve productivity
Using AI for code review, refactoring, and testing
Quickly researching new technologies and implementing solutions with AI support
About Me
Hi, I am a Fullstack Developer specializing in POS system development with over 5 years of experience in .NET (C#, .NET Core, Web API) and SQL Server optimization.
I focus on building stable, high-performance applications for retail and payment systems.
