This a jQuery UI custom build, downloaded from: http://jqueryui.com/download/#!version=1.11.4&components=1111111111110111111111111111111111111 It includes all components except the datepicker, because it conflicts with bootstrap-datepicker that is packaged with Shiny. The copy of jQuery that is bundled with the download, under external/, is not included because Shiny already has its own copy of jQuery.