Guide · Open source
How to use ASP.NET Core: get started, contribute and build apps
Updated · written with AI from the project's own documentation and checked against our catalogue data
ASP.NET Core is an open-source, cross-platform framework from the .NET platform for building internet-connected applications such as web apps, IoT apps and mobile backends. This guide is for developers who already write C# or .NET code and want to know how to get the framework, what you need installed, and where to go next. By the end you will know how to get the source, which download to pick, and where the official getting-started material lives.
ASP.NET Coredotnet/aspnetcore · ★ 38.5k · MIT Install options & downloads Quick start
- 1Check the prerequisites. Confirm that you are working in C# or .NET and install the .NET SDK. The README recommends the SDK if you are unsure which download you need.
- 2Read the Getting Started guide. Open the Getting Started instructions on learn.microsoft.com to follow the official first steps.
- 3Clone the repository. Run git clone https://github.com/dotnet/aspnetcore to get the source code locally.
- 4Build from source if needed. Follow the docs/BuildFromSource.md guide in the repository if you want to build the framework yourself.
- 5Run and develop on your platform. Develop and run your ASP.NET Core apps on Windows, Mac or Linux, deploying to the cloud or on-premises servers.
- 6Contribute back. Pick a help wanted or good first issue, or file an issue, following CONTRIBUTING.md.
What ASP.NET Core is and who it is for
ASP.NET Core is designed to run in the cloud or on your own servers. The project describes it as modular, with minimal overhead, so you keep flexibility when you build a solution. You can develop and run ASP.NET Core apps on Windows, Mac and Linux.
It is a developer framework. It is written for C# and .NET developers building web apps or HTTP APIs, and it is not a no-code website builder.
- Good fit: C# and .NET developers, teams deploying to the cloud or on-premises servers, and people who want a cross-platform server framework under the MIT license.
- Not a fit: people who do not write C# or .NET code, and beginners with no programming background who need more basic learning first.
What you need before you start
The main prerequisite listed is the .NET SDK. The README notes that if you are unsure which download you need, you should install the SDK, because it has everything except the IIS plugin.
ASP.NET Core apps run on .NET, which the project describes as a free, cross-platform and open-source application runtime.
- .NET SDK (recommended if you are unsure which download to choose)
- Optional: the Windows Hosting Bundle, if you need the IIS plugin (ASP.NET Core Module)
Get the source code with git
To work with the repository itself, clone it from GitHub. The README gives this command for the main repository.
git clone https://github.com/dotnet/aspnetcoreGet started with the official instructions
For a first project, follow the Getting Started instructions on the Microsoft Learn site. The README also points to the .NET homepage for released versions of .NET, getting-started guides and learning resources.
The README links the Learn documentation as the main reference for ASP.NET Core. The documentation sources are kept in a separate repository named Documentation.
- Getting Started: https://learn.microsoft.com/aspnet/core/getting-started
- ASP.NET Core documentation: https://learn.microsoft.com/aspnet/core/
- Released .NET versions: https://www.microsoft.com/net
Use daily builds and build from source
The README lists nightly builds of the ASP.NET Core Shared Framework for Windows, macOS and Linux, including Linux musl variants. Use these if you want pre-release binaries rather than the released versions. A separate guide explains how to build the source code yourself.
If you are unsure which build you need, the README advises installing the SDK rather than picking individual binaries.
- Daily builds guide: docs/DailyBuilds.md
- Build from source guide: docs/BuildFromSource.md
- Windows Hosting Bundle includes the Shared Framework, the .NET Runtime Shared Framework and the IIS plugin (ASP.NET Core Module)
Contribute, report issues and find related projects
The README says some of the best ways to contribute are to try things out, file issues, join design conversations and make pull requests. Start with the contributing page to see where to log issues and start discussions. Issues labelled help wanted and good first issue are the README's suggested starting points.
Security issues and bugs should be reported privately to the Microsoft Security Response Center through the MSRC Researcher Portal, not in public issues. Related repositories include Entity Framework Core for data access, the Runtime, and Razor for .cshtml and .razor files.
- Contributing guide: CONTRIBUTING.md
- Triage process: docs/TriageProcess.md
- Security policy: SECURITY.md
- Community standup: streamed weekly on YouTube
What people use it for
- Building web apps written in C# on .NET
- Creating HTTP APIs and mobile backends
- Deploying internet-connected services to the cloud or on-premises servers
- Working on a large open-source framework by picking up help wanted or good first issue tasks
- Hosting ASP.NET Core apps on Windows with IIS using the Hosting Bundle
Frequently asked questions
Is ASP.NET Core free to use?
The repository is licensed under the MIT License, as shown on the project's badge and LICENSE.txt file. The README describes .NET, which ASP.NET Core apps run on, as free, cross-platform and open source.
What do I need installed to use ASP.NET Core?
The README lists the .NET SDK as the prerequisite. It advises installing the SDK if you are unsure which download you need, since it contains everything except the IIS plugin.
Can I run ASP.NET Core on Mac and Linux?
Yes. The project says you can develop and run ASP.NET Core apps cross-platform on Windows, Mac and Linux.
How do I clone the ASP.NET Core source code?
Run git clone https://github.com/dotnet/aspnetcore. The README gives this as the install command for the repository.
Where do I report a security bug in ASP.NET Core?
Report security issues and bugs privately to the Microsoft Security Response Center through the MSRC Researcher Portal, rather than in a public issue. The README says you should receive a response within 24 hours.
How does ASP.NET Core compare with Express, Django, Spring Boot or Ruby on Rails?
Express, Django, Spring Boot and Ruby on Rails are comparable projects, but the source does not compare them in detail. Choose ASP.NET Core if you want to write C# on .NET; choose one of the others if your team uses JavaScript, Python, Java or Ruby.
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Our verdict
ASP.NET Core suits C# and .NET developers who want a modular, cross-platform, MIT-licensed framework for web apps, HTTP APIs and cloud or on-premises services. If you do not write C# or .NET, want a no-code website builder, or are new to programming, pick a more beginner-friendly option or learn the basics first.
Install options & downloads