A new tab in developer tools is added called Open UI. When accessing an Open UI enabled Siebel url the interface will provide you with the current view you are in and all applets associated with the current view. Clicking on the applets will run a get rawrecordset, returning the data associated to that applet in JSON format. 

This tool is aimed at Siebel developer and testers, there is custom panel that allows users to get a profile attribute, choose from the pre-selected list or enter a custom value. 

There is also a logout button that will send the logout command – useful for testers and for bespoke Open UI applications that perhaps don’t provide a logout button.

Update --

The ability to go to a view by passing in the view name is now possible and you can also set custom profile attributes alongside getting them ( you need to have this enabled on your Siebel platform for this to work )