OS X

/Users/"your username"/Library/KapturePad

On the latest versions of OS X, the user Library folder is hidden. To access it, click on Go in the Finder's menubar while holding the alt key. The Library will appear in the drop-down-menu.


Windows

XP/Vista — C:\Documents and Settings\<username>\KapturePad
Windows 7 — C:\Users\<username>\KapturePad