Framework · Since 2016

ASP.NET Core

ASP.NET Core is Microsoft's open-source, cross-platform web framework for building fast web APIs, web apps and real-time services in C#.

Start the guide Discussions

ASP.NET Core is an open-source web framework that runs on .NET. Released in 2016 as a ground-up redesign of the original ASP.NET, it can be developed and run on Windows, macOS and Linux. The Kestrel web server, dependency injection, a middleware pipeline, configuration and logging are built in, so a server application works without assembling the basics yourself.

ASP.NET Core is widely used where performance and maintainability both matter: REST APIs, enterprise line-of-business systems and microservices. On one foundation you can choose concise minimal APIs, MVC controllers, Razor Pages or Blazor, work with databases through Entity Framework Core and add real-time features with SignalR. The SDK also supports building container images and deploying to the cloud.

To get started, install the .NET SDK, create an empty project with dotnet new web, and follow the official Microsoft Learn tutorial to build a minimal API. Knowing basic C# makes everything easier. From there, move on to dependency injection, middleware, configuration and EF Core to cover what real projects need.

Highlights

High performance

The lightweight built-in Kestrel server and an asynchronous programming model let apps handle many requests with modest resources.

Built-in DI and middleware

Service registration, the request pipeline, configuration and logging are part of the framework, giving every app a consistent structure.

Several programming models

Minimal APIs, MVC controllers, Razor Pages and Blazor share the same routing and middleware, so you can pick and mix them as needed.

Cross-platform and cloud-ready

Apps run on Windows, macOS and Linux, with per-environment configuration, health checks and container image builds for operations.

Where it is used

REST APIs and gRPC services
Enterprise web applications
Container-based microservices
Real-time web apps with SignalR

Install

1
Install the .NET SDK
Download and install the .NET SDK for your operating system from dotnet.microsoft.com. ASP.NET Core is included; afterwards, check that the SDK is listed.
```
dotnet --list-sdks
```
2
Create a project
Create an empty ASP.NET Core project from the web template. If you are building an API from the start, the webapi template is another good choice.
```
dotnet new web -o HelloWeb
```
3
Run the dev server
Move into the project folder and start the app with dotnet watch. Edits are applied with Hot Reload; open the address printed in the console.
```
cd HelloWeb && dotnet watch
```

Your first program

First project

This is the Program.cs created by dotnet new web. WebApplication.CreateBuilder sets up configuration, logging, dependency injection and the Kestrel server, and MapGet registers an endpoint that returns a string for GET requests to /. app.Run() starts the server: run dotnet run and open the address shown in the console to see Hello World!.

Program.cs

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

app.MapGet("/", () => "Hello World!");

app.Run();

dotnet new web -o HelloWeb && cd HelloWeb && dotnet run

Everyday tools

dotnet CLI: The command-line tool in the .NET SDK. It creates projects, adds packages, and builds, runs, tests and publishes apps.
Visual Studio: Microsoft's IDE for Windows. Debug, profile and send HTTP requests to ASP.NET Core projects in one place.
C# Dev Kit: The official Visual Studio Code extension for C#, with solution management, IntelliSense, debugging and a test explorer.
Entity Framework Core: The official ORM for .NET. Work with databases through C# classes and manage the schema with migrations.

Step-by-step guide

Six chapters that take you from installation to the core ideas of ASP.NET Core.

Official docs and resources

Languages

C#C# is an object-oriented language from Microsoft for building web, desktop, game and cloud applications on .NET with a single language.

Discussions

Start a discussion

Ask questions, share experience and trade opinions about ASP.NET Core.

No discussions yet. Start the first one.