Microsoft open sourced Visual Studio Code Extension for Arduino

https://www.open-electronics.org/microsoft-open-sourced-visual-studio-code-extension-for-arduino/

Microsoft, which has the biggest contributor community on GitHub, has launched the MIT-licensed code across the open source platform to enable developers to leverage Arduino hardware specifically for IoT projects and applications. 

The design builds on the official Arduino IDE, meaning that the extension is almost entirely compatible and consistent with Arduino IDE.
Microsoft announcement: Arduino has been open sourced on GitHub.com at https://github.com/Microsoft/vscode-arduino!