XAML is acronym for eXtensible Application Markup Language (and pronounced “Zammel”) and it is used for developing Silverlight Application. XAML can be written using any text editor like Notepad++, EditPlus or Simply Notepad, but after writing XAML there is a need to check whether XAML is working properly or not. There are tools available for running XAML application including Visual Studio or Microsoft Expression Blend. But there are some other ways also that can be used to run and test you XAML Application
SilverlightPad can only be used for testing Silverlight 1.0 applications.
KaXAML is a windows application and it can be used to test Silverlight 2.0 applications also. On the right hand side KaXAML has a XAML pane where you can put or type XAML code. LaXAML also has a small toolbar comes very handy for taking snapshots, filling colors and performing some basic tasks.