A while back I blogged about Debugging visual tree/layout issues in Silverlight and on Windows Phone. My little helper library – the VisualTreeDebugger has been updated for WinRT and is available as part of the WinRT XAML Toolkit project that I have been working on recently. I also mentioned that you could use Silverlight Spy to debug your Windows Phone app, but it was not free. Well, now it seems like Koen Zwikstra has come up with a new version that, for a limited time, is free and it is called XAML Spy. Grab it while you can!