To debug the Optimizely Content Management System (CMS) user interface, you can run your site with uncompressed JavaScript in edit view. To do this, you need to enable debug mode for client resources by adding \<clientResources debug="true" /> to your _web.config_ inside the `episerver.framework` element. You can then toggle the debug files on and off by changing the value of the debug attribute from true to false.

The CMS UI NuGet packages contain all the JavaScript files required to run the user interface compressed into a zip file. The system then reads the contents of the zip file at run time. At initialization, if the client resources debug flag is set to **true**, the system first looks for a debug version of the JavaScript zip file and, if it exists, loads that instead.

### EPiServer.CMS.UI.Sources

The _EPiServer.CMS.UI.Sources_ NuGet package contains all original user interface source files together with uncompressed Dojo and Dijit.

The source package is built as part of every release so it ties quite simply into the continuous release cycle. You can install it the same way you would any other NuGet package from [nuget.episerver.com](🔗).

If you need to manipulate sources files and then create a customized Dojo build you can use this package. It comes together with all Dojo build tools.

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Note

To debug the CMS edit view, you do not need this package. The change described above is sufficient.