Safari extensions provide similar functionality to extensions for other browsers, but there are some important differences. This document points out some things you should be aware of and highlights some of the pieces you will use to build a Safari extension. If you have already written Google Chrome extensions, Firefox extensions, or Greasemonkey scripts, then this document is a great place to get started with Safari extensions.
Safari Extensions Development Guide provides comprehensive detail about how Safari Extensions work and how to build an extension.
Safari Extensions Reference provides specific details about the JavaScript classes used to develop extensions.
Last updated: 2010-08-03