Create a Minimal Web API with .NET Core

This tutorial walks you through building a simple RESTful Web API using .NET 8 minimal APIs.

Prerequisites

Visual Studio 2022 or VS Code
.NET SDK 8.0 or later
Basic knowledge of C# and HTTP

Step 1 – Create a New Project

Open a terminal and run:

dotnet new webapi -o WeatherApi

Navigate to the project folder:

cd WeatherApi

Step 2 – Define a Model

Create a file Models/WeatherForecast.cs with the following content:

namespace WeatherApi.Models;

public class WeatherForecast
{
    public DateTime Date { get; set; }

    public int TemperatureC { get; set; }

    public string? Summary { get; set; }

    public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
}

Step 3 – Add the Endpoint

Edit Program.cs to expose a GET endpoint:

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

var summaries = new[] { "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching" };

app.MapGet("/weatherforecast", () =>
{
    var forecast = Enumerable.Range(1, 5).Select(index =>
        new WeatherApi.Models.WeatherForecast
        {
            Date = DateTime.Now.AddDays(index),
            TemperatureC = Random.Shared.Next(-20, 55),
            Summary = summaries[Random.Shared.Next(summaries.Length)]
        })
        .ToArray();
    return forecast;
});

app.Run();

Step 4 – Run the API

Start the application:

dotnet run