If you ever needed to export xsltlistviewwebpart webpart you might’ve noticed that the usual Export webpart menu is unavailable. Here is a workaround, thanks to the tip of Anatoly Mironov:
In SharePoint there is a hidden application page that exports web parts: /_vti_bin/exportwp.aspx. This page takes two query parameters:
•pageurl. The absolute url of the page where the web part resides that you want to export
•guidstring. The guid that is called webpartid in the markup on the page
So, suppose, you have this site: https://intranet.sharepoint.com and a web part (id: 0c3adfe9-8f5d-4432-918a-42410e4e324d) on a page https://intranet.sharepoint.com/SitePages/Home.aspx
This will be the resulting URL to export your webpart:
Paste it into the web browser address bar and you’ll download an xml file with your web part definition. This method works in SharePoint 2010 and SharePoint 2013 and even in SharePoint Online (Office 365).