.NET Web API Complete Crash Course 2026 | Build REST APIs from Scratch using C# and Dapper

In this complete .NET Web API crash course (2026), you’ll learn how to build REST APIs using ASP.NET Core from scratch.
This beginner-friendly tutorial covers everything you need to start backend development with C# and .NET Web API.

Whether you’re preparing for interviews, learning backend development, or building real projects - this video gives you a solid foundation.

📌 What You Will Learn
What is Web API and how it works
REST API concepts (GET, POST, PUT, DELETE)
Creating a .NET Web API project
Controllers & routing
Model binding & validation
HTTP status codes & responses
Dependency Injection (DI) basics
Connecting Web API with SQL Server
Dapper Core basics
Swagger / OpenAPI
Best practices for real-world APIs

🛠 Technologies Used

C#
.NET 8 / .NET 9
ASP.NET Core Web API
SQL Server
Dapper
Swagger

⏱ Timestamps :
00:00:00 - Introduction
00:00:39 - Understanding what is API (Client and Server)
00:01:53 - What is REST API (Core Principles)
00:03:58 - HTTP Verbs
00:04:34 - HTTP Response Status Codes
00:06:43 - Creating Web API Project
00:08:32 - Understanding Program.cs file
00:10:37 - Creating a new API controller
00:14:08 - Testing "Hello World" endpoint in Swagger
00:15:47 - Minimal Program.cs file for API
00:16:55 - Controller with two GET endpoints
00:19:08 - Setting up SQL Server Database and Table
00:20:29 - Creating EmployeeController
00:21:24 - Setting up database connection string in appsettings.json
00:22:30 - HTTP GET - Fetch all employees
00:23:20 - Understanding project architecture
00:24:52 - Creating new folders for Service and Repo layer
00:26:24 - Creating IEmployeeRepository and EmployeeRepository
00:28:28 - Installing Dapper
00:29:33 - Fetching connection string from appsettings
00:30:44 - Completing employee/all endpoint
00:37:02 - Testing our endpoint
00:37:44 - Understanding dependency injection
00:39:24 - Understanding how request was processed
00:40:16 - HTTP GET specific employee by ID
00:49:11 - HTTP POST - Create new employee
00:54:12 - HTTP PUT - Updating existing employee
01:00:36 - HTTP DELETE - Remove employee
01:04:38 - HTTP PATCH - Change department of employee
01:11:28 : Thank you