Vistascript is a scripting development environment and runtime for WinFx. The developer includes a syntax highlighting editor, winform designer, class and file browsers, interactive debugger, compiler and ftp based editor support for remote scripts. The runtime interpreter supports XMPP, JSON, REST and SOAP protocols and can import/export native PHP or Smalltalk data.

The Vistascript language is modelled after the Javascript 2.0 proposal with extensions such as Smalltalk block closures. Vistascript is designed for building Ajax style applications on Windows Vista and workgroup or game applications over the Google instant messaging service.
The Vistascript runtime is a bytecode interpreter which can dynamically load Winforms stored in XML format or WPF controls stored in XAML format. Callbacks are dynamically assigned after controls have been loaded.

A version of the Vistascript runtime is planned for the Microsoft WPF/E browser plugin during the summer of 2006.