Jekyll Short URL uses Goo.gl as a back-end and a small Script on your 404 page.
PLEASE NOTE THAT GOOGLE HAS SHUT DOWN GOO.GL
How To
Place this in your 404 page.
<script>if (window.location.href.indexOf("sh") > -1) {var shortCode = document.location.href.substring( document.location.href.lastIndexOf( '/' ) );window.location.href = "https://goo.gl" + shortCode; }</script>
To use your Jekyll Short URL simply navigate toyourblog.com/sh/shorturl.