Implementation of PHP Console for WordPress.
WordPress Plugin for debugging and learning with and at the application.
Debug Bar Extension for the Timber Library
Ever wondered which actions and filters were slowing down your WordPress site? You're welcome.
Plugin for Debugging WordPress Plugin Activation Errors. Instead of seeing: "The plugin generated ### characters of unexpected output during activation. If you notice “headers already sent” messages, problems with syndication feeds or other issues, try deactivating or removing this plugin." you get the errors being thrown.