Tipue Search is a site search engine jQuery plugin. It's free, open source, responsive and fast. Tipue Search only needs a browser that supports jQuery. It doesn't need MySQL or similar. In Static mode it doesn't even need a web server.
There's full documentation at http://www.tipue.com/search/docs/.
Copyright and license
Tipue Search Copyright (c) 2017 Tipue, under the The MIT License.