DotNet Web API Mastery Docs
Back to CourseBeginner5 min read
DotNet Web API /

Setting Up the .NET SDK and Tools

Install the .NET SDK, check it works from the terminal, pick an editor, and learn the handful of dotnet CLI commands you will use every day.

Bishal Biswas

Bishal Biswas

Self Learner

Published on: September 1, 2026
Last updated: September 7, 2026
Beginner Topic

What you actually need

To build a Web API you need three things:

  1. The .NET SDK, which contains the compiler, the runtime and the dotnet command
  2. An editor, such as Visual Studio, Visual Studio Code or Rider
  3. A way to send test requests, such as the built in Swagger page or a .http file

That is it. No web server to install, no database to set up yet. The SDK ships with a server called Kestrel that runs your API locally.

Installing the .NET SDK

Go to the official download page at dotnet.microsoft.com/download and pick the latest LTS version. LTS means Long Term Support, so it gets fixes for three years. Choose the SDK, not the Runtime. The Runtime can only run apps. The SDK can build them.

On Windows you can also use winget:

winget install Microsoft.DotNet.SDK.8

On macOS with Homebrew:

brew install --cask dotnet-sdk

On Ubuntu:

sudo apt-get update
sudo apt-get install -y dotnet-sdk-8.0

Checking that it worked

Open a fresh terminal. A new terminal matters, because the installer changes your PATH and an old window will not see it.

dotnet --version

You should see something like 8.0.404. If you get “command not found”, close every terminal, open a new one, and try again. If it still fails, the installer did not add dotnet to your PATH.

To see everything installed on the machine:

dotnet --info

This prints your SDK versions, your runtimes and your operating system. It is the first thing to paste when you ask someone for help.

Choosing an editor

Any of these work well. Pick the one you are comfortable with.

Visual Studio on Windows is the heaviest option and the most guided. It has a visual debugger, NuGet package UI and scaffolding menus. Install the “ASP.NET and web development” workload.

Visual Studio Code is light and cross platform. Install the C# Dev Kit extension. This gives you IntelliSense, debugging and test running.

JetBrains Rider is a paid cross platform IDE that many .NET developers prefer.

This course uses the terminal for commands so it works with all three.

The dotnet CLI commands you will use

Almost everything you do goes through the dotnet command. Here are the ones that matter.

Create a project from a template:

dotnet new webapi -n MyApi

Restore the NuGet packages a project depends on. Modern commands do this automatically, so you rarely run it alone:

dotnet restore

Build the project, which compiles it and reports errors:

dotnet build

Run the project. This builds first, then starts the server:

dotnet run

Watch the project. This is the one you will actually use. It restarts the API whenever you save a file:

dotnet watch run

Add a NuGet package to the project in the current folder:

dotnet add package Serilog.AspNetCore

Run tests in a test project:

dotnet test

To see every available template:

dotnet new list

Solutions, for when one project is not enough

A real API usually grows into several projects: the API itself, a class library for your data code, and a test project. A solution file groups them so one command builds them all.

dotnet new sln -n Shop

dotnet new webapi -n Shop.Api
dotnet new classlib -n Shop.Data
dotnet new xunit -n Shop.Tests

dotnet sln add Shop.Api Shop.Data Shop.Tests

Then let one project use another:

dotnet add Shop.Api reference Shop.Data

Now dotnet build at the solution level builds everything in the right order. You do not need this on day one, but it is good to know the shape.

Trusting the local HTTPS certificate

ASP.NET Core serves HTTPS locally using a self signed development certificate. Your browser will not trust it until you say so:

dotnet dev-certs https --trust

Run this once per machine. On Windows and macOS a prompt appears. Accept it. Without this you get certificate warnings every time you open the API in a browser.

Global tools

Some tools install once and work everywhere. The Entity Framework Core tool is the one you will need later for database migrations:

dotnet tool install --global dotnet-ef

Check it:

dotnet ef --version

To update it later:

dotnet tool update --global dotnet-ef

A quick smoke test

Let us prove the whole toolchain works before moving on:

dotnet new webapi -n HelloApi
cd HelloApi
dotnet run

The terminal prints something like:

Now listening on: https://localhost:7042
Now listening on: http://localhost:5042

Open the HTTPS address in a browser and add /swagger to the end. You should see a documentation page listing the sample endpoint. Press Ctrl+C in the terminal to stop the server.

If you got that far, your machine is ready.

Common problems

The port is already in use. Another copy of the API is still running. Close it, or change the port in Properties/launchSettings.json.

dotnet is not recognised. Your PATH is stale. Open a new terminal. On Linux, log out and back in.

The browser warns about the certificate. You skipped dotnet dev-certs https --trust.

Packages fail to restore. You are offline, or behind a proxy that blocks nuget.org.

Quick recap

  • Install the .NET SDK, not just the runtime, and prefer the latest LTS version.
  • Confirm the install with dotnet --version in a brand new terminal.
  • dotnet new, dotnet build, dotnet run and dotnet watch run cover most daily work.
  • dotnet watch run restarts the API on every save, so use it while developing.
  • Run dotnet dev-certs https --trust once so local HTTPS stops warning you.
  • Install dotnet-ef as a global tool now. You will need it when the database chapters start.
Program.cs

// Program.cs - a first API you can use to confirm your setup works.
// 1) dotnet new webapi -n HelloApi
// 2) cd HelloApi
// 3) dotnet watch run
var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();
// A plain text endpoint: the simplest thing that can possibly work
app.MapGet("/", () => "The API is running.");
// A JSON endpoint. The framework serializes the object for you.
app.MapGet("/api/environment", (IWebHostEnvironment env) => new
{
    Application  = env.ApplicationName,
    Environment  = env.EnvironmentName,                       // Development
    DotNetVersion = Environment.Version.ToString(),           // e.g. 8.0.11
    Os           = System.Runtime.InteropServices.RuntimeInformation.OSDescription,
    StartedAtUtc = DateTime.UtcNow
});
// A health endpoint you can call to check the server is awake
app.MapGet("/api/ping", () => Results.Ok(new { status = "ok" }));
app.Run();

Previous

C# Concepts You Need for ASP.NET Core Web API

Next

Your First Web API Project

Was this explanation helpful?

Your feedback helps us improve the content for everyone.