Safari has long had a hidden Debug menu that contains some very useful capabilities. When Apple rolled out Safari 4, many of these capabilities found their way into Safari’s Develop menu. The hidden Debug menu still exists, though, and offers plenty of helpful resources, even if you aren’t a developer.
Enable Safari 4 Debug Menu
- Launch Terminal, located at /Applications/Utilities/Terminal.
- Enter the following command line into Terminal. You can copy/paste the text into Terminal, or you can simply type the text as shown. The command is a single line of text, but your browser may break it into multiple lines. Be sure to enter the command as a single line in Terminal.
- Press enter or return.
- Relaunch Safari. The new Debug menu will be available.
defaults write com.apple.Safari IncludeInternalDebugMenu 1 Disable Safari 4’s Debug Menu
If for some reason you want to disable the Debug menu, you can do so at any time, using Terminal.- Launch Terminal, located at /Applications/Utilities/Terminal.
- Enter the following command line into Terminal. You can copy/paste the text into Terminal, or you can simply type the text as shown. The command is a single line of text, but your browser may break it into multiple lines. Be sure to enter the command as a single line in Terminal.
- Press enter or return.
- Relaunch Safari. The Debug menu will be gone.
defaults write com.apple.Safari IncludeInternalDebugMenu 0 
