.NET is open source and cross-platform and is maintained by Microsoft and the .NET community on GitHub. .NET consistently ranks among the top 30 most active open source projects since 2017, as tracked by the Cloud Native Computing Foundation.
All aspects of .NET Core are open source including class libraries, runtime, compilers, languages, ASP.NET Core web framework, Windows desktop frameworks, Entity Framework Core data access library, and more.
Yes, we do accept contributions! As with any open source project, we don't just blindly accept everything. The pull requests we receive are reviewed for quality and to ensure they align with the goals of .NET.
We've already accepted over 100,000 contributions from developers from over 3,700 companies outside Microsoft.
The various parts of .NET are maintained in different GitHub repositories. These repositories typically use the MIT or Apache 2 licenses. Some repositories license documentation and other forms of content under Creative Commons Attribution 4.0.
To understand the license used, see specific repositories.
The .NET Foundation is an independent, non-profit organization established to support an innovative, commercially friendly, open source ecosystem around the .NET platform.
Over 50 open source projects are part of the .NET Foundation. Microsoft as well as others like VMware (formerly Pivotal), Google, Samsung, and Red Hat have made significant contributions, in addition to our broader community. See how you can get involved with the .NET Foundation.
In addition to the code, we aim to make every aspect of .NET as open as possible. The documentation is open source. You can also track what is being built via themesof.net. On the .NET team at Microsoft, we opened up our day-to-day work with initiatives like our open API review process and the community standups.
The Open source library guidance provides recommendations for .NET developers to create high-quality .NET libraries. The guidance itself is open source on GitHub and developed in partnership with popular library authors.
You can build your own version of .NET from source code, but most production apps need a supported version of the platform.
Microsoft ships official releases that are built and tested on Microsoft-maintained servers in Azure and supported just like any Microsoft product. See the .NET support policy for details.
Red Hat supports .NET Core on Red Hat Enterprise Linux (RHEL). Red Hat builds .NET Core from source and makes it available in the Red Hat Software Collections. Red Hat and Microsoft collaborate to ensure that everything works well on RHEL.