The Debugger is at the bottom of the Yahoo Pipes editor. It shows you the various stages of your Pipe output while you work on it.
The Debugger will show the output of the currently selected module (with an orange header bar instead of blue). To show the final output of the Pipe, make sure your modules are connected to the “Pipe Output” and select that. To make sure the Debugger shows the most up to date information, you’ll need to hit the refresh button when you make changes to anything.
You can use the Debugger to examine each part of your Yahoo Pipe and make sure it’s functioning properly. By default, the Debugger will show the titles of each item in a feed; to drill down the data get more information about each item, click the small triangle to the left of each item.