C# extension works well and uses Roslyn Language Server that is part[0] of the Roslyn (C# compiler) itself - this is what the base C# extension[1] uses. Both of

C# extension works well and uses Roslyn Language Server that is part[0] of the Roslyn (C# compiler) itself - this is what the base C# extension[1] uses. Both of these are licensed under MIT. The closed-source part is 'vsdbg' which is Visual Studio's debugger shipped as a component that the extension uses. It, however, can be replaced with Samsung's 'NetCoreDbg' by using the extension fork[2]. [0]: https://github.com/dotnet/roslyn/tree/main/src/LanguageServer https://github.com/dotnet/roslyn/tree/main/src/LanguageServe... [1]: https://github.com/dotnet/vscode-csharp https://github.com/dotnet/vscode-csharp [2]: https://github.com/muhammadsammy/free-vscode-csharp https://github.com/muhammadsammy/free-vscode-csharp (please consider giving it a star, it's the only actively maintained alternative and other tools end up relying on it downstream to support debugging - VSCodium as well as Emacs and Neovim with VSC extension bridges)