The C# part of the Unity engine and editor source code is provided here for reference purposes only.

For terms of use, please visit https://unity3d.com/legal/licenses/Unity_Reference_Only_License

The repository contains third-party code subject to third-party notices.

Please note that the terms of use prohibit the modification or redistribution of the C# code, whether in source or binary form. If you intend to modify Unity's source code (C# and C++), please contact Unity sales for a commercial source code license: https://store.unity.com/contact?type=source-code

At this time, We do not accept pull requests. However, if you come across what appears to be a bug, we appreciate it if you could report it using the Unity Bug Reporter. For more information, refer to our blog post: https://blogs.unity3d.com/2018/03/26/releasing-the-unity-c-source-code/

Unless expressly provided otherwise, the software under this license is provided strictly on an "AS IS" BASIS WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED. Please review the license for details on these and other terms and conditions.

The C# solution is in Projects/CSharp/UnityReferenceSource.sln

The folder and file layout of the reference source match the Unity source tree layout it can and will change between different Unity versions.