Fess supports adding a search box to your website.
Set the following code where you would like to place the search box of the website.
<script> (function() { var fess = document.createElement('script'); fess.type = 'text/javascript'; fess.async = true; fess.src = '//<Server Name>/js/ss/fess-ss.min.js'; fess.charset = 'utf-8'; fess.setAttribute('id', 'fess-ss'); fess.setAttribute('fess-url', '//<Server Name>/json'); var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(fess, s); })(); </script> <fess:search></fess:search>