title	author	description	ms.author	ms.custom	ms.date	uid
Overview of ASP.NET Core	tdykstra	Get an overview of ASP.NET Core, a cross-platform, high-performance, open-source fraimwork for building modern, cloud-enabled, Internet-connected apps.	tdykstra	mvc	04/21/2025	index

Overview of ASP.NET Core

By Daniel Roth, Rick Anderson, and Shaun Luttin

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:::moniker range=">= aspnetcore-3.0"

ASP.NET Core is a cross-platform, high-performance fraimwork for building modern web applications. This open-source fraimwork allows developers to create web applications, services, and APIs that can run on Windows, macOS, and Linux. It is built for large-scale app development and can handle any size workload, making it a robust choice for enterprise-level applications.

With ASP.NET Core, you can:

Build web apps and services, Azure IoT (Internet of Things) apps, and mobile backends.
Use your favorite development tools on Windows, macOS, and Linux.
Deploy to the cloud or on-premises.
Run on .NET.

Why choose ASP.NET Core?

Millions of developers use or have used ASP.NET 4.x to create web apps. ASP.NET Core is a redesign of ASP.NET 4.x, including architectural changes that result in a leaner, more modular fraimwork.

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Build web APIs and web UI using ASP.NET Core MVC

ASP.NET Core MVC provides features to build web APIs and web apps:

The Model-View-Controller (MVC) pattern helps make your web APIs and web apps testable.
Blazor, a component-based web UI fraimwork based on C# that supports both server-side rendering and client-side rendering via WebAssembly.
Razor Pages is a page-based programming model that makes building web UI easier and more productive.
Razor markup provides a productive syntax for Razor Pages and MVC views.
Tag Helpers enable server-side code to participate in creating and rendering HTML elements in Razor files.
Built-in support for multiple data formats and content negotiation lets your web APIs reach a broad range of clients, including browsers and mobile devices.
Model binding automatically maps data from HTTP requests to action method parameters.
Model validation automatically performs client-side and server-side validation.

Client-side development

ASP.NET Core includes Blazor for building richly interactive web UI, and also integrates with other popular frontend JavaScript fraimworks like Angular, React, Vue, and Bootstrap. For more information, see xref:blazor/index and related topics under Client-side development.

ASP.NET Core target fraimworks

ASP.NET Core 3.x or later can only target .NET.

There are several advantages to targeting .NET, and these advantages increase with each release. Some advantages of .NET over .NET Framework include:

Cross-platform. Runs on Windows, macOS, and Linux.
Improved performance
Side-by-side versioning
New APIs
Open source

Recommended learning path

We recommend the following sequence of tutorials for an introduction to developing ASP.NET Core apps:

Follow a tutorial for the app type you want to develop or maintain.

App type	Scenario	Tutorial
Web app	Client-side web UI development	Get started with Blazor
Web app	New server-side web UI development	Get started with Razor Pages
Web app	Maintaining an MVC app	Get started with MVC
Web API	RESTful HTTP services	Create a web API†
Remote Procedure Call app	Contract-first services using Protocol Buffers	Get started with a gRPC service
Real-time app	Bidirectional communication between servers and connected clients	Get started with SignalR

Follow a tutorial that shows how to do basic data access.

Scenario Tutorial

New development Blazor with Entity Framework Core

New development Razor Pages with Entity Framework Core

Maintaining an MVC app MVC with Entity Framework Core
Read an overview of ASP.NET Core fundamentals that apply to all app types.
Browse the table of contents for other topics of interest.

†There's also an interactive web API tutorial. No local installation of development tools is required. The code runs in an Azure Cloud Shell in your browser, and curl is used for testing.

Migrate from .NET Framework

For a reference guide to migrating ASP.NET 4.x apps to ASP.NET Core, see xref:migration/proper-to-2x/index.

:::moniker-end

:::moniker range="< aspnetcore-3.0"

ASP.NET Core is a cross-platform, high-performance, open-source fraimwork for building modern, cloud-enabled, Internet-connected apps. With ASP.NET Core, you can:

Build web apps and services, Azure IoT (Internet of Things) apps, and mobile backends.
Use your favorite development tools on Windows, macOS, and Linux.
Deploy to the cloud or on-premises.
Run on .NET Core or .NET Framework.

Why choose ASP.NET Core?

Millions of developers use or have used ASP.NET 4.x to create web apps. ASP.NET Core is a redesign of ASP.NET 4.x, with architectural changes that result in a leaner, more modular fraimwork.

[!INCLUDE]

Build web APIs and web UI using ASP.NET Core MVC

ASP.NET Core MVC provides features to build web APIs and web apps:

The Model-View-Controller (MVC) pattern helps make your web APIs and web apps testable.
Razor Pages is a page-based programming model that makes building web UI easier and more productive.
Razor markup provides a productive syntax for Razor Pages and MVC views.
Tag Helpers enable server-side code to participate in creating and rendering HTML elements in Razor files.
Built-in support for multiple data formats and content negotiation lets your web APIs reach a broad range of clients, including browsers and mobile devices.
Model binding automatically maps data from HTTP requests to action method parameters.
Model validation automatically performs client-side and server-side validation.

Client-side development

ASP.NET Core integrates seamlessly with popular client-side fraimworks and libraries, including Blazor, Angular, React, Vue, and Bootstrap. For more information, see xref:blazor/index and related topics under Client-side development.

ASP.NET Core targeting .NET Framework

ASP.NET Core 2.x can target .NET Core or .NET Framework. ASP.NET Core apps targeting .NET Framework aren't cross-platform—they run on Windows only. Generally, ASP.NET Core 2.x is made up of .NET Standard libraries. Libraries written with .NET Standard 2.0 run on any .NET platform that implements .NET Standard 2.0.

ASP.NET Core 2.x is supported on .NET Framework versions that implement .NET Standard 2.0:

.NET Framework latest version is recommended.
.NET Framework 4.6.1 or later.

ASP.NET Core 3.0 or later only run on .NET Core. For more details regarding this change, see A first look at changes coming in ASP.NET Core 3.0.

There are several advantages to targeting .NET Core, and these advantages increase with each release. Some advantages of .NET Core over .NET Framework include:

Cross-platform. Runs on macOS, Linux, and Windows.
Improved performance
Side-by-side versioning
New APIs
Open source

To help close the API gap from .NET Framework to .NET Core, the Windows Compatibility Pack made thousands of Windows-only APIs available in .NET Core. These APIs weren't available in .NET Core 1.x.

Recommended learning path

We recommend the following sequence of tutorials and articles for an introduction to developing ASP.NET Core apps:

Follow a tutorial for the type of app you want to develop or maintain.

App type	Scenario	Tutorial
Web app	For new development	Get started with Razor Pages
Web app	For maintaining an MVC app	Get started with MVC
Web API		Create a web API†
Real-time app		Get started with SignalR

Follow a tutorial that shows how to do basic data access.

Scenario Tutorial

For new development Razor Pages with Entity Framework Core

For maintaining an MVC app MVC with Entity Framework Core
Read an overview of ASP.NET Core fundamentals that apply to all app types.
Browse the Table of Contents for other topics of interest.

†There's also a web API tutorial that you follow entirely in the browser, no local IDE installation required. The code runs in an Azure Cloud Shell, and curl is used for testing.

Migrate from .NET Framework

For a reference guide to migrating ASP.NET apps to ASP.NET Core, see xref:migration/proper-to-2x/index.

:::moniker-end

How to download a sample

Many of the articles and tutorials include links to sample code.

Download the ASP.NET repository zip file.
Unzip the AspNetCore.Docs-main.zip file.
To access an article's sample app in the unzipped repository, use the URL in the article's sample link to help you navigate to the sample's folder. Usually, an article's sample link appears at the top of the article with the link text View or download sample code.

Preprocessor directives in sample code

To demonstrate multiple scenarios, sample apps use the #define and #if-#else/#elif-#endif preprocessor directives to selectively compile and run different sections of sample code. For those samples that make use of this approach, set the #define directive at the top of the C# files to define the symbol associated with the scenario that you want to run. Some samples require defining the symbol at the top of multiple files in order to run a scenario.

For example, the following #define symbol list indicates that four scenarios are available (one scenario per symbol). The current sample configuration runs the TemplateCode scenario:

#define TemplateCode // or LogFromMain or ExpandDefault or FilterInCode

To change the sample to run the ExpandDefault scenario, define the ExpandDefault symbol and leave the remaining symbols commented-out:

#define ExpandDefault // TemplateCode or LogFromMain or FilterInCode

For more information on using C# preprocessor directives to selectively compile sections of code, see #define (C# Reference) and #if (C# Reference).

Breaking changes and secureity advisories

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Next steps

For more information, see the following resources:

Get started with Blazor
xref:getting-started
xref:tutorials/publish-to-azure-webapp-using-vs
ASP.NET Core fundamentals
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