In this presentation, we introduce a new development toolset to support the new Tizen app model (Xamarin.Forms on Tizen C# platform) for Linux, MacOS and Windows. We firstly present 'Visual Studio Code (vscode) extension for Tizen' that enables you to develop Tizen .NET apps through Visual Studio Code. Our goal for this tool is to offer "cradle to grave" feature for developing a Tizen .NET app. With our extenion, you can simply create an Tizen .NET project, edit, build and debug it. Packaging, installing and running it on the target or the emulator are also supported. We also present the Tizen baseline SDK which is a foundation of our vscode extension to make it more powerful. Through this session, we will walk through major features of vscode extension and the baseline SDK by demonstrating how to develop Tizen .NET app. At the end of session, our future plans for this toolset will be presented. See you in the session!