That is a customised version of the XPages Extension Library demo application. The custom version was created by Mark Leusink - http://linqed.eu/ & http://bootstrap4xpages.com/
However, the only difference to the standard verison of the demo app is the theme being used. You can thus use the nsf provided in the extlib download, like so:
- install extlib release v901_00_10 or later to your server & Designer
- extract the
XPagesExt.nsf
from the extlib zip you downloaded, to your server
- open the NSF in Domino Designer
- open the
xsp.properties
of the application
- change the application theme to
Bootstrap3.2.0
or Bootstrap3.2.0_flat
- save and re-build the application
- open the app in a browser