jqrambo

The most comprehensive scroll-to-top plugin in the universe. Provides an intuitive button on each page so that, with one click, your readers will be back to the top of the page. Fully customisable from within the Customizer. You can change almost any setting and even upload your own custom image.

CakePress Scroll to top

The most comprehensive scroll-to-top plugin in the universe. Filled with useful features, every aspect can tweaked or customized from within the Custo …

Satoshi Yoshida

Will add smooth scroller in your website.
[Document] http://beek.jp/smooth-scroller/

CakePress Scroll to top vs Smooth Scroller